Method of tunnel containing structures

• US 3,919,768 A
• Filed: 01/02/1973
• Issued: 11/18/1975
• Est. Priority Date: 01/02/1973
• Status: Expired due to Term

• Current Assignee: Northrop Corporation (Northrop Grumman Corporation)
• Original Assignee: Norman J. Grossman, Richard D. Pittman, Ronald E. Johnson
• Inventors: Pittman, Richard D., Grossman, Norman J., Johnson, Ronald E.
• Primary Examiner(s): Drummond, Douglas J.
• Assistant Examiner(s): Massie, Jerome W.
• Application Number:
  US05/320,066
• Time in Patent Office: 1,050 Days
• Field of Search: 117/239,234 156/3,155,272,305,204,217,300 96/35.1,36,36Z 340/174PW,174VA 29/604,591
• US Class Current: 29/604
• CPC Class Codes: G11C 11/38 using tunnel diodes
• CPC Class Codes: Y10T 156/1036 Bending of one piece blank and joining edges to form article
• CPC Class Codes: Y10T 29/49069 Data storage inductor or core

Abstract

A tunnel containing structure which is capable of functioning as a magnetic memory device, a circuit device, such as a fluid circuit device, or the like and which is primarily constructed from photo-resist materials using photographic techniques. The tunnel containing structure is made by depositing a photo-resist coating on a substrate surface, partially exposing the resist coating to radiation having a proper spectral distribution and thereafter immediately depositing an additional coating on the first named coating so that the two become firmly bonded together. By exposing the second coating through a mask having selected spaced apart transparent areas and developing the latter coating in response to the exposure it is possible to produce channels in the second coating. A cover member is then bonded to the upper surface of the second coating through an additional layer of photo-resist material to form the tunnels. The structure can be used in the fabrication of magnetic storage devices, for example, by inserting driving wires in the tunnels and including conductive lines such as word straps on the substrate and the cover member.

Claims

1. THE METHOD OF MAKING A THREE DIMENSIONAL STRUCTURE OF SELECTED SIZEE IN EACH DIMENSION FORMED OF A POLYMERIZABLE RADIATION ACTIVATABLE MATERIAL, SAID METHOD COMPRISING:

A. DEPOSITING A FIRST LAYER OF A RADIATION ACTIVE MATERIAL ON A SUBSTRATE, B. EXPOSING SAID FIRST LAYER TO A SOURCE OF RADIATION HAVING A SPECTRAL DISTRIBUTION COMPATIBLE WITH THE SPECTRAL RESPONSE OF SAID RADIATION ACTIVE MATERIAL TO ONLY PARTIALLY ACTIVE SAID LAYER, C. IMMEDIATELY THEREAFTER DEPOSITING A SECOND LAYER OF RADIATION ACTIVE MATERIAL ON SAID FIRST LAYER TO PERMIT CO-POLYMERIZATION OF SAID TWO LAYERS BEWEEN THE INTERFACE THEREBETWEEN TO THEREBY PERMANTENTLY BOND SAID TWO LAYERS, B. BAKING SAID STRUCTURE TO HOMOGENIZE THE INTERFACE BETWEEN SAID LAYERS,

2. The method of making the structure of claim 1 further characterized in that the method includes bonding an additional member to an exposed surface of said second layer parallel to the surface of the substrate.

3. The method of making the structure of claim 1 further characterized in that the second layer is exposed to said source of radiation through a mask which permits exposure of only said selected portion.

4. The method of making the structure of claim 1 further characterized in that the treating of the material comprises washing the material in a solvent so that the unexposed portions are washed away.

5. The method of making a device having a plurality of spaced apart tunnels therein, said method comprising:

a. coating a radiation active resist material on one planar surface of a substrate having a pair of opposite planar surfaces;

b. exposing a plurality of spaced apart selected areas of said resist material to a source of radiation, c. treating the resist material with an agent capable of removing portions thereof not exposed to the source of radiation to thereby form a plurality of spaced apart recesses separated by a plurality of spaced apart ridges and in which said recesses have walls extending between said ridges which are substantially parallel to the first named planar surface, d. coating a material capable of bonding action on one planar surface of a cover member, e. and bonding said cover member to the outwardly presented surface of said ridges through the material capable of bonding actIon to form tunnels with said recesses.

6. The method of claim 5 further characterized in that the coating of radiation active resist material on the substrate is accomplished by applying a first layer of such material to the planar surface of said substrate and exposing said first layer to said source of radiation to effect only partial activation thereof, and a second layer of radiation active resist material is thereafter applied to said partially activated first layer, whereby copolymerization occurs between the two layers to effect bonding therebetween, said device then being baked to homogenize the interface between said layers.

7. The method of claim 6 further characterized in that said second layer is exposed to said source of radiation through a mask which permits exposure of only said selected spaced apart areas.

8. The method of claim 5 further characterized in that said cover member is integral with and initially substantially coplanar with said substrate and folded over and bonded to said ridges after coating with said resist material and exposure to cause partial activation thereof.

9. The method of claim 5 further characterized in that the material capable of bonding action is a radiation active resist material and the last named coating is exposed to a source of radiation to cause partial activation thereof immediiatelly prior to bonding whereby copolymerization occurs between the last named coating and the material of said ridges.

10. The method of claim 7 further characterized in that the method includes the applying of heat and pressure to the ridges and cover member during the bonding operation.

11. The method of fabricating a magnetic memory device comprising:

a. coating a radiation active resist material on one planar surface of a substrate also having a plurality of electrical conductors located with respect to one planar surface thereof, b. exposing a plurality of spaced apart selected areas of said resist material to a source of radiation in such manner that the exposed selected areas are angularly located with respect to said electrical conductors, c. treating the resist material with an agent capable of removing portions thereof not exposed to the source of radiation to thereby form a plurality of spaced apart recesses separated by a plurality of spaced apart ridges and in which said ridges are substantially parallel to the first named planar surface and angularly located with respect to the electrical conductors, d. bonding a cover member having a plurality of electrical conductors thereon to the surfaces of said ridges parallel to said substrate planar surface to form tunnels with said recesses, so that respective ones of the conductors on said cover member and substrate are in substantial registry and capable of being in electrical contact, e. and inserting electrically conductive elements in said tunnels.

12. The method of claim 11 further characterized in that the surface of the cover member which is bonded to the surfaces of said ridges is first coated with a radiation active resist material and exposed to a source of radiation to cause partial activation thereof prior to bonding to said ridges, whereby copolymerization occurs at the interface between the ridges and the last mentioned resist material.

13. The method of claim 11 further characterized in that the radiation active resist material is applied to a planar surface of said substrate which is opposite to the planar surface on which said electrical conductors are located.

14. The method of claim 11 further characterized in that the electrical conductors on said cover member are located on one planar surface thereof and that the opposite planar surface of said cover member is first coated with a bondable material so that said cover member is bonded to the surfaces of said ridges parallel to said substrate surface through said bondable material.

15. The method of claim 14 further charaCterized in that the electrical conductors on said cover member are located with respect to one planar surface thereof and that the same planar surface of said cover member is first coated with a bondable material so that said cover member is bonded to the surfaces of said ridges through said last named coating of bondable material, and the radiation active resist material applied to said substratee is applied to the same planar surface on which said electrical conductors are located.

16. The method of claim 12 further characterized in that said cover member is integral with and initially substantially coplanar with said substrate and folded over and bonded to said ridges after coating with said resist material and exposure thereof.