Methods for forming a MRAM with non-orthogonal wiring
The present subject matter allows non-orthogonal lines to be formed at the same thickness as the orthogonal lines so as to promote compact designs, to be formed with even line edges, and to be formed efficiently. Various method embodiments relate to forming a magnetic random access memory (MRAM) array. Various embodiments include forming a first wiring layer of approximately parallel conductors, a second wiring layer of approximately parallel conductors and a third wiring layer of approximately parallel conductors such that the first, second and third wiring layers cross at a number of intersections. At least one of the first, second and third wiring layers are formed so as to be non-orthogonal with respect to a remaining at least one of the first, second and third wiring layers. The method further includes forming a layer of magnetic storage elements proximately located to the intersections. Other aspects are provided herein.
1. A method for forming a magnetic random access memory (MRAM) array, comprising:
forming a first wiring layer of approximately parallel word conductors, a second wiring layer of approximately parallel bit conductors and a third wiring layer of approximately parallel select conductors such that the word, bit and select conductors in the first, second and third wiring layers cross at a number of intersections;
at least one of the first, second and third wiring layers being formed so as to be non-orthogonal with respect to a remaining at least one of the first, second and third wiring layers; and
forming a layer of magnetic storage elements, wherein the magnetic storage elements are proximately located to the intersections and are magnetically coupled to magnetic fields generated when current flows in word lines, when current flows in bit lines, and when current flows in select lines, wherein a desired magnetic storage element is written using three magnetic fields, wherein the three magnetic fields used to write the desired magnetic storage element include a first magnetic field produced by an energized word conductor in the first wiring layer, a second magnetic field produced by an energized bit conductor in the second wiring layer, and a third magnetic field produced by an energized select conductor in the third wiring layer.
2. The method of claim 1 , wherein the MRAM array is formed in a wafer, the method further comprising forming a number of alignment markings on the wafer.
3. The method of claim 2 , wherein forming the number of alignment markings on the wafer includes forming the number of alignment marking when forming the first wiring layer.
4. The method of claim 1 , wherein the MRAM array is formed in a wafer, the method further comprising rotating the wafer between at least two wiring layers.
5. The method of claim 4 , wherein forming the layer of magnetic storage elements includes forming the layer of magnetic storage elements after forming the first wiring layer and before forming the second wiring layer.
6. The method of claim 5 , further comprising forming an insulator layer after forming the second wiring layer and before forming the third wiring layer.
7. The method of claim 1 , wherein forming the layer of magnetic storage elements includes forming magnetoresistance devices electrically coupled to two of the wiring layers.
8. A method for forming a magnetic random access memory (MRAM) array, comprising:
forming a first wiring layer of approximately parallel word conductors on a wafer using a first data set when a work piece is at a first rotational position θ 1 ;
forming a second wiring layer of approximately parallel bit conductors on the wafer using a second data set when the work piece is at a second rotational position θ 2 such that the bit conductors of the second wiring layer cross with the word conductors of the first wiring layer at a number of intersections, wherein the second wiring layer is non-orthogonal to the first wiring layer;
forming a third wiring layer of approximately parallel select conductors such that the select conductors of the third wiring layer cross the word conductors of the first wiring layer and the bit conductors of the second wiring layer at the number of intersections; and
forming a layer of magnetic storage elements, wherein the magnetic storage elements are proximately located to the intersections and are magnetically coupled to magnetic fields generated when current flows in word lines, when current flows in bit lines, and when current flows in select lines, wherein a desired magnetic storage element is written using three magnetic fields, wherein the three magnetic fields used to write the desired magnetic storage element include a first magnetic field produced by an energized word conductor in the first wiring layer, a second magnetic field produced by an energized bit conductor in the second wiring layer, and a third magnetic field produced by an energized select conductor in the third wiring layer.
9. The method of claim 8 , wherein forming the layer of magnetic storage elements includes forming the layer of magnetic storage elements after forming the first wiring layer and before forming the second wiring layer.
10. The method of claim 9 , further comprising forming an insulator layer after forming the second wiring layer and before forming the third wiring layer.
11. The method of claim 8 , wherein forming the third wiring layer includes forming the third wiring layer using a third data set when the work piece is at a third rotational position θ 3 .
12. The method of claim 8 , wherein forming the layer of magnetic storage elements includes forming magnetoresistance devices electrically coupled to two of the wiring layers.
13. The method of claim 8 , wherein forming the second wiring layer includes registering the wafer using a number of alignment markings.
14. The method of claim 13 , further comprising forming the alignment markings when forming the first wiring layer.
15. The method of claim 13 , wherein forming the first wiring layer includes registering the wafer using the number of alignment markings.
16. A method for forming a magnetic random access memory (MRAM) array, comprising:
forming a first wiring layer of approximately parallel word conductors using a first reticle;
forming a second wiring layer of approximately parallel bit conductors using a second reticle such that the bit conductors of the second wiring layer cross with the word conductors of the first wiring layer at a number of intersections;
forming a third wiring layer of approximately parallel select conductors using a third reticle such that the select conductors of the third wiring layer cross the word conductors of the first wiring layer and the bit conductors of the second wiring layer at the number of intersections; and
forming a layer of magnetic storage elements, wherein the magnetic storage elements are proximately located to the intersections and are magnetically coupled to magnetic fields generated when current flows in word lines, when current flows in bit lines, and when current flows in select lines,
wherein at least one of the first wiring layer, the second wiring layer and the third wiring layer is formed so as to be non-orthogonal with respect to a remaining at least one of the first wiring layer, the second wiring layer and the third wiring layer, and
wherein a desired magnetic storage element is written using three magnetic fields, wherein the three magnetic fields used to write the desired magnetic storage element include a first magnetic field produced by an energized word conductor in the first wiring layer, a second magnetic field produced by an energized bit conductor in the second wiring layer, and a third magnetic field produced by an energized select conductor in the third wiring layer.
17. The method of claim 16 , wherein:
the first reticle is created at a first rotational position θ 1 ;
the second reticle is created at a second rotational position θ 2 ;
the third reticle is created at a third rotational position θ 3 ;
the first rotational position θ 1 and the second rotational position θ 2 are such that a set of parallel lines in the first wiring layer form an angle of approximately 60° with respect to a set of parallel lines in the second wiring layer; and
the second rotational position θ 2 and the third rotational position θ 3 are such that the set of parallel lines in the second wiring layer form an angle of approximately 60° with respect to a set of parallel lines in the third wiring layer.
18. The method of claim 17 , wherein the second reticle is properly aligned at the second rotational position θ 2 and the third reticle is properly aligned at the third rotational position θ 3 using a number of alignment markings.
19. A magnetic random access memory (MRAM) array formed by a method, comprising:
forming a first wiring layer of approximately parallel word conductors using a first reticle;
forming a second wiring layer of approximately parallel bit conductors using a second reticle such that the bit conductors of the second wiring layer cross with the word conductors of the first wiring layer at a number of intersections;
forming a third wiring layer of approximately parallel select conductors using a third reticle such that the select conductors of the third wiring layer cross the word conductors of the first wiring layer and the bit conductors of the second wiring layer at the number of intersections; and
forming a layer of magnetic storage elements, wherein the magnetic storage elements are proximately located to the intersections and are magnetically coupled to magnetic fields generated when current flows in word lines, when current flows in bit lines, and when current flows in select lines,
wherein at least one of the first wiring layer, the second wiring layer and the third wiring layer is formed so as to be non-orthogonal with respect to a remaining at least one of the first wiring layer, the second wiring layer and the third wiring layer, and
wherein a desired magnetic storage element is written using three magnetic fields, wherein the three magnetic fields used to write the desired magnetic storage element include a first magnetic field produced by an energized word conductor in the first wiring layer, a second magnetic field produced by an energized bit conductor in the second wiring layer, and a third magnetic field produced by an energized select conductor in the third wiring layer.
20. The MRAM array of claim 19 , wherein the magnetic storage elements includes magnetoresistance devices electrically coupled between two of the wiring layers.