Process for manufacturing a group comprising at least two elements, one whereof includes an encapsulated micro-integrated structure, and thereby obtained group

• US 6,638,836 B1
• Filed: 11/30/2000
• Issued: 10/28/2003
• Est. Priority Date: 02/02/2000
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Alessandri, Alberto, Ratti, Francesco, Murari, Bruno, Vigna, Benedetto, Sassolini, Simone
• Primary Examiner(s): Elms, Richard
• Assistant Examiner(s): SMITH, BRADLEY
• Application Number:
  US09/727,608
• Time in Patent Office: 1,062 Days
• Field of Search: 438/459, 438/455, 438/460, 438/458, 257/723
• US Class Current: 438/459
• CPC Class Codes: G11B 5/5552 using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means

Abstract

The manufacture process includes: forming a first wafer of semiconductor material housing integrated electronic components forming a microactuator control circuit and a signal preamplification circuit; forming microactuators, each including a rotor and a stator, in a surface portion of a second wafer of semiconductor material; attaching the second wafer to the first wafer, with the surface portion of the second wafer facing the first wafer; thinning the second wafer; attaching the second wafer to a third wafer to obtain a composite wafer; thinning the first wafer; cutting the composite wafer into a plurality of dice connected to a protection chip; removing the protection chip; attaching read/write transducers to the dice; and attaching the dice to supporting blocks for hard-disk drivers.

Claims

1. A process for manufacturing a unit of at least two elements, comprising the steps of:

forming a first wafer;

forming micro-electromechanical structures in a surface portion of a second wafer of semiconductor material;

attaching said second wafer to said first wafer, with said surface portion of the second wafer facing said first wafer;

thinning said second wafer down to a first desired thickness;

attaching said second wafer to a third wafer to obtain a composite wafer;

cutting said composite wafer into a plurality of dice respectively fixed to a plurality of protection chips; and

removing the protection chips.

2. The process according to claim 1, wherein said micro-electromechanical structures are microactuators, each comprising a rotor and a stator, and said first wafer is of semiconductor material and houses integrated electronic components forming a microactuator control circuit and a signal preamplification circuit.

3. The process according to claim 2, wherein after removing said protection chips, read/write transducers are attached to said dice and said dice are attached to supporting blocks for hard-disk drivers.

4. The process according to claim 2, wherein forming encapsulation structures for said micro-electromechanical structures.

5. The process according claim 1, wherein said step of forming microelectromechanical structures comprises the steps of:

in a semiconductor substrate of the second wafer, forming first and second trenches delimiting a central supporting region, an intermediate supporting region, and an external supporting region;

filling said first and second trenches with immobilization material;

forming, on top of said semiconductor substrate, electric insulation regions and sacrificial regions;

growing a semiconductor layer over said semiconductor substrate;

defining stator regions and rotor regions in said semiconductor layer, said stator regions and rotor regions being separated laterally from each other and from an outer portion of said semiconductor layer by third and fourth trenches; and

removing said sacrificial regions through said third and fourth trenches.

6. The process according to claim 5, wherein said step of thinning said second wafer comprises removing part of said semiconductor substrate as far as said first and second trenches, and after thinning said second wafer and before attaching said second wafer to a third wafer, said immobilization material is removed from said first and second trenches.

7. The process according to claim 5 wherein, after thinning said second wafer and before attaching said second wafer to a third wafer, metal contact regions are further formed on top of said semiconductor substrate.

8. The process according to claim 7, wherein said step of forming metal contact regions comprises forming a closed-shape sealing region surrounding said first trench, and after removing said protection chip, a third element is attached to said metal contact regions.

9. The process according to claim 7 wherein, simultaneously with said metal contact regions, vertical stop regions are formed that limit movements of said rotor with respect to said stator.

10. The process according to claim 1, wherein said step of attaching said second wafer to a third wafer comprises forming adhesive regions of removable material and having a closed shape on top of said semiconductor substrate, said adhesive regions surrounding at the top regions of said semiconductor substrate where said micro-electromechanical structures are formed.

11. The process according to claim 10, wherein said step of forming adhesive regions of removable material comprises the step of:

forming a lead-tin layer on the third wafer; and

defining said lead-tin layer.

12. The process according to claim 11, wherein said step of forming adhesive regions of removable material comprises the step of:

forming a nickel layer on the third wafer before forming said lead-tin layer; and

forming a double layer of chromium-gold on the top of said semiconductor substrate.

13. The process according to claim 10, wherein said removable material is removable with hot air jets arranged in front of sides of said third wafer.

14. The process according to claim 1, wherein said step of attaching said second wafer to a third wafer comprises forming adhesive regions of removable material.

15. The process according to claim 14, wherein said removable material is a gel.

16. The process according to claim 14, wherein said third wafer comprises protruding portions defining cavities, each cavity housing a respective microactuator and characterized in that said gel is deposited on said protruding portions and said cavities.

17. The process according to claim 1, wherein said step of attaching said second wafer to said first wafer comprises the steps of:

forming at least first and second attachment regions on said first chip and, respectively, on said surface portion of said second wafer, said first and second attachment regions having a congruent shape, and said second attachment regions surrounding areas of said surface portions where said micro-electromechanical structures are formed; and

attaching together said first and second attachment regions.

18. The process according to claim 17, wherein said first attachment regions are of electrically conductive material and are formed simultaneously with electric connection regions.

19. The process according to claim 1 wherein, after attaching said second wafer to a third wafer, said first wafer is thinned to a second desired thickness.