Wafer planarization using a uniform layer of material and method and apparatus for forming uniform layer of material used in semiconductor processing

• US 6,410,459 B2
• Filed: 08/14/2001
• Issued: 06/25/2002
• Est. Priority Date: 09/02/1999
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Gordon, Brian F., Blalock, Guy T., Stroupe, Hugh E.
• Primary Examiner(s): Ghyka, Alexander G.
• Application Number:
  US09/930,022
• Publication Number:
  US 20020015753A1
• Time in Patent Office: 315 Days
• Field of Search: 438/692, 438/758, 438/760, 438/633, 438/781, 438/780, 438/782, 425/412
• US Class Current: 438/782
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 43/021 characterised by the shape of the surface
• CPC Class Codes: B29K 2023/16 EPM, i.e. ethylene-propylene copolymers; EPDM, i.e. ethylene-propylene-diene copolymers; EPT, i.e. ethylene-propylene terpolymers
• CPC Class Codes: B29K 2027/12 containing fluorine
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29L 2031/3061 Number plates
• CPC Class Codes: B29L 2031/7728 Disc-shaped records B29L2017/003
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers

Abstract

In connection with wafer planarization, an apparatus for forming a layer of material having a substantially uniform thickness and substantially parallel first and second major surfaces includes a pair of pressing elements and a stop. Each of the pair of pressing elements has a flat pressing surface. The pressing surfaces are opposed to one another and operable to compress a quantity of the material therebetween. The stop is positioned at least partially between the pressing surfaces and has a thickness substantially equal to the desired uniform thickness of the layer. The stop is positioned to establish a spacing between the flat pressing surfaces that is substantially equal to the thickness of the stop and thereby to the desired uniform thickness of the layer when the pressing elements engage the stop. As a result, engagement of the stop by the pressing surfaces during pressing of the material forms a layer of the material of substantially uniform thickness with substantially parallel major surfaces formed by the flat pressing surfaces. The layer is then used in semiconductor processing to provide a flat surface on a layer of a substrate assembly, thereby enhancing the planarization of the substrate assembly.

Claims

1. A method of forming a layer of material on a substrate assembly comprising:

introducing material for forming the layer into an open central region of a stop;

disposing the stop at least partially between first and second flat pressing surfaces;

pressing the material between the first and second flat pressing surfaces, wherein the stop is configured to limit the extent to which the first and second flat pressing surfaces approach one another during pressing to thereby form a layer of material having a substantially uniform thickness; and

applying the layer of material to a surface of the substrate assembly.

2. The method of claim 1, further comprising pressing the layer of material against the surface of the substrate assembly with a pressing apparatus so as to planarize the surface of the substrate assembly.

3. The method of claim 2, further comprising removing the layer of material from the planarized surface of the substrate assembly.

4. The method of claim 1, wherein the method further comprises providing a substrate assembly having an epoxy layer, applying the layer of material to a surface of the epoxy layer, and pressing the layer of material against the epoxy layer to planarize the surface of the epoxy layer.

5. The method of claim 1, wherein the stop has a plurality of inwardly extending, spaced-apart projections circumscribing the open central region and material receiving recesses defined between adjacent projections, and wherein pressing the material between the first and second flat pressing surfaces causes excess material to flow into the material receiving recesses.

6. A method of forming a layer of material on a substrate assembly comprising:

soaking the material at a soaking temperature below a melting point of the material until a temperature throughout the material is substantially uniform;

pressing the material between first and second flat pressing surfaces;

positioning a stop between the first and second flat pressing surfaces to limit the extent to which the first and second flat pressing surfaces approach one another during pressing to thereby form a layer of material with first and second major surfaces being formed by the first and second flat pressing surfaces, respectively, the layer of material having a substantially uniform thickness;

removing the layer of material from the first and second flat pressing surfaces; and

placing the layer of material over a surface of the substrate assembly.

7. The method of claim 6, further comprising pressing the layer of material against the surface of the substrate assembly to planarize the surface of the substrate assembly.

8. The method of claim 6, further comprising pressing the layer of material against the surface of the substrate assembly with a pressing apparatus to planarize the surface of the substrate assembly such that the layer of material prevents the surface of the substrate assembly from adhering to the pressing apparatus.

9. The method of claim 7, wherein the thickness of the layer of material does not vary more than about five millionths of an inch.

10. A method of forming a layer of a material on a substrate assembly comprising:

providing first and second flat pressing surfaces for pressing the material;

positioning a shim between the first and second flat pressing surfaces;

pressing the material between the first and second flat pressing surfaces to form a layer of material, the shim being configured to limit the extent to which the first and second flat pressing surfaces approach one another during pressing so as to define the thickness of the layer of material, the layer of material having first and second major surfaces formed by the first and second flat pressing surfaces, respectively, and wherein the first and second major surfaces are within about fifty angstroms of being flat and the thickness of the layer of material does not vary more than about five millionths of an inch; and

applying one of the first and second major surfaces to a surface of the substrate assembly.

11. The method of claim 10, wherein the layer of material is transparent to ultraviolet radiation.

12. The method of claim 10, wherein the shim has an open central region for receiving material for forming the layer of material and a plurality of inwardly extending, spaced-apart projections circumscribing the open central region with material receiving recesses defined between adjacent projections, and wherein pressing the material between the first and second flat pressing surfaces causes excess material to flow into the material receiving recesses.

13. A method of forming a layer of a material on a substrate assembly comprising:

heating the material until the material has a substantially uniform temperature that is below the melting point of the material;

pressing the material between first and second flat pressing surfaces to form a layer of material having first and second major surfaces formed by the first and second pressing surfaces, respectively, and wherein the first and second major surfaces are within about fifty angstroms of being flat and the layer of material has a thickness between the first and second major surfaces that does not vary greater than about five millionths of an inch;

disposing the layer of material at least partially between a surface of the substrate assembly and a third pressing surface; and

planarizing the surface of the substrate assembly by pressing the layer of material against the surface of the substrate assembly with the third pressing surface.

14. A method of forming a layer of a material on a substrate assembly comprising:

heating the material;

pressing the material between first and second flat pressing surfaces;

disposing a stop between the first and second pressing surfaces to limit the extent to which the first and second pressing surfaces approach one another during pressing to thereby form a layer of substantially uniform thickness having first and second major surfaces with the first and second major surfaces being formed by the flat pressing surfaces; and

applying one of the first and second major surfaces to a surface of a substrate assembly.

15. The method of claim 14 wherein the heating act comprises heating the material until the material transitions to a plastic state without melting the material.

16. The method of claim 14 wherein the substrate assembly has an epoxy layer and the applying act comprises applying one of the first and second major surfaces of the layer to a surface of the epoxy layer of the substrate assembly.