METHOD FOR MANUFACTURING A MAGNETIC MEMORY ELEMENT ARRAY USING HIGH ANGLE SIDE ETCH TO OPEN TOP ELECTRICAL CONTACT

• US 20190214553A1
• Filed: 01/09/2018
• Published: 07/11/2019
• Est. Priority Date: 01/09/2018
• Status: Active Grant

• Current Assignee: Integrated Silicon Solution Incorporated (Uphill Investment Co.)
• Original Assignee: Spin Memory, Inc.
• Inventors: Gajek, Marcin, Ryan, Eric Michael, Pinarbasi, Mustafa
• Granted Patent: US 10,446,742 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/32131 by physical means only
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/80 Constructional details

Abstract

A method for manufacturing a magnetic memory element array. A plurality of magnetic memory elements are formed on a substrate, and a dielectric fill layer such as SiO2 or SiNx is deposited over the magnetic memory element pillars. An ion milling is then performed at a high angle (at least 70 degrees) relative normal to remove topographic dielectric features from areas over the magnetic memory elements. Optionally, additional ion milling processes can be performed at increasing angles relative to normal until the dielectric material has been removed from the areas over the magnetic memory elements.

Claims

1. A method for manufacturing high density pillar structures, the method comprising:

forming magnetic memory element pillars over a substrate;

depositing a dielectric material over the magnetic memory element pillars and substrate;

performing a first high angle ion milling to remove a portion of the dielectric material, the high angle ion milling being performed at an angle of at least 70 degrees relative to normal with a rotating chuck; and

after performing the first ion milling, performing a second ion milling at an angle relative to normal that is greater than the angle of the first ion milling.

3. The method as in claim 1, further comprising performing sequential ion milling processes at increasing angles relative to normal.

4. The method as in claim 1, wherein the magnetic memory element pillars are formed with a hard mask structure at their top, the method further comprising performing sequential ion milling processes at increasing angles relative to normal and terminating the ion milling when the hard mask has been exposed.

5. The method as in claim 1, wherein the dielectric material comprises one or more of SiO₂, Si₃N₄, SiC or Al2O3.

6. The method as in claim 1, wherein the dielectric material is deposited at least to the height of the top of the magnetic memory element pillars.

7. The method as in claim 1, wherein the magnetic memory element pillars are formed with hard mask layers at their top and wherein the dielectric layer is deposited at least to the level of the hard mask layer.

8. The method as in claim 1, wherein the forming of the magnetic memory element pillars further comprises:

depositing a magnetic memory element layer;

depositing a hard mask layer;

depositing a photoresist layer;

photolithographically patterning the photoresist layer to form a photoresist mask;

performing a reactive ion etching to transfer the image of the photoresist mask onto the hard mask; and

performing an ion milling to remove portions of the magnetic memory element that are not protected by the hard mask to form magnetic memory element pillars.

9. The method as in claim 8, wherein the ion milling process used to form the magnetic memory element pillars is performed at one or more angles relative to normal to form vertical side walls on the magnetic memory element pillars.

2. (canceled)

10. A method for manufacturing high density pillar structures, the method comprising:

forming magnetic memory element pillars over a substrate, the memory element pillars having a hard mask layer formed at their top, the hard mask layer having an end point detection layer incorporated therein;

depositing a dielectric material over the magnetic memory element pillars and substrate;

performing a first high angle ion milling to remove a portion of the dielectric material, the high angle ion milling being performed at an angle of at least 70 degrees relative to normal with a rotating chuck; and

after performing the first ion milling performing a second ion milling at an angle relative to normal that is greater than the angle of the first ion milling.

11. The method as in claim 10, wherein the end point detection layer comprises Mg.

13. The method as in claim 10, further comprising performing sequential ion milling processes at increasing angles relative to normal.

14. The method as in claim 10, further comprising performing sequential ion milling processes at increasing angles relative to normal and terminating the ion milling when the end point detection layer has been detected.

15. The method as in claim 10, further comprising after performing the ion milling performing a second ion milling at an angle relative to normal that is greater than the angle of the first ion milling, and terminating the second ion milling when the end point detection layer has been detected.

16. The method as in claim 10, further comprising terminating the ion milling process when the end point detection layer has been detected, the end point detection layer being detected by secondary ion mass spectroscopy.

17. The method as in claim 10, wherein the dielectric material comprises one or more of SiO₂, Si₃N₄, SiC or Al2O3.

18. The method as in claim 10, wherein the dielectric material is deposited at least to the height of the top of the magnetic memory element pillars.

19. The method as in claim 10, wherein the dielectric layer is deposited at least to the level of the hard mask layer.

20. The method as in claim 10, wherein the forming of the magnetic memory element pillars further comprises:

depositing a magnetic memory element layer;

depositing the hard mask layer;

depositing a photoresist layer;

photolithographically patterning the photoresist layer to form a photoresist mask;

performing a reactive ion etching to transfer the image of the photoresist mask onto the hard mask; and

performing an ion milling to remove portions of the magnetic memory element that are not protected by the hard mask to form magnetic memory element pillars.

12. (canceled)