Microdevice with movable microplatform and process for making thereof

• US 20040144653A1
• Filed: 01/27/2003
• Published: 07/29/2004
• Est. Priority Date: 01/27/2003
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Topart, Patrice, Jerominek, Hubert
• Granted Patent: US 6,849,170 B2
• Time in Patent Office: Days
• US Class Current: 205/67
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: C25D 1/003 3D structures, e.g. superposed patterned layers
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A process for making a microdevice that includes the steps of providing a base member and selectively electroforming a support member for supporting a microplatform with respect to the base member. The process also includes the steps of selectively electroforming the microplatform and forming a flexible hinge member for hingedly connecting the microplatform to the support member and allowing relative movement of the microplatform with respect to the support member. This microdevice, when compared to prior art devices, can have improved mechanical strength, rigidity, low deformation, and high planarity.

Claims

1. A process for making a microdevice (1), comprising the steps of:

a) providing a base member;

b) selectively electroforming at least one support member (4) for supporting a microplatform (2) with respect to the base member;

c) selectively electroforming the microplatform (2); and

d) forming at least one flexible hinge member (3) for hingedly connecting the microplatform (2) to said at least one support member (4) and allowing relative movement of the microplatform (2) with respect to said at least one support member (4).

2. The process for making the microdevice (1) according to claim 1, wherein:

step b) comprises the step of mountably connecting said at least one support member (4) to the base member;

step d) is performed after step b) and before step c) and comprises the step of mountably connecting said at least one hinge member (3) to said at least one support member (4); and

step c) comprises the step of mountably connecting the microplatform (2) to said at least one hinge member (3).

3. The process for making the microdevice (1) according to claim 1, wherein:

step c) is performed before steps a), b) and d) and comprises the step of selectively electroforming the microplatform (2) on a sacrificial substrate (20);

step d) is performed before steps a) and b) and comprises the step of mountably connecting said at least one hinge member (3) to the microplatform (2);

step b) is performed before step a) and comprises the steps of mountably connecting said at least one support member (4) to said at least one hinge member (3), and removing the sacrificial substrate (20); and

step a) comprises the step of mountably connecting said at least one support member (4) to the base member.

4. The process for making the microdevice (1) according to claim 2, wherein step d) comprises the step of selectively electroforming said at least one hinge member on said at least one support member (4).

5. The process for making the microdevice (1) according to claim 4, wherein step a) comprises the steps of:

i) providing a substrate (5);

ii) connecting at least one electrode (6) and at least one contact pad (8) onto a side of the substrate (5);

iii) covering said side with a protective layer (9); and

iv) providing at least one opening (10) in the protective layer (9) for accessing said at least one contact pad (8).

6. The process for making the microdevice (1) according to claim 5, wherein step b) comprises the steps of:

v) covering, after step iv), said side with a first seed layer (11);

vi) covering, after step v), said side with a first photoresist layer (12); and

vii) photolitographically patterning the first photoresist layer (12) to produce at least one opening (13) on the first photoresist layer (12) that is aligned with said at least one opening (10) for accessing said at least one contact pad (8), said at least one support member (4) being selectively electroformed in said at least one opening (13) of the first photoresist layer (12).

7. The process for making the microdevice (1) according to claim 6, wherein step d) comprises the steps of:

viii) covering, after step vii), said side with a second seed layer (14);

ix) covering the second seed layer (14) with a second photoresist layer (15); and

x) photolitographically patterning the second photoresist layer (15) to produce at least one opening (16) on the second photoresist layer (15) that is aligned with said at least one support member (4), said at least one hinge member (3) being selectively electroformed in said at least one opening (16) of the second photoresist layer (15).

8. The process for making the microdevice (1) according to claim 7, wherein step c) comprises the steps of:

xi) removing, after step x), the second photoresist layer (15);

xii) covering, after step xi), said side with a third photoresist layer (17);

xiii) photolitographically patterning the third photoresist layer (17) to produce an opening (18) on the third photoresist layer (17), the microplatform (2) being selectively electroformed in the opening (18) of the third photoresist layer (17);

xiv) removing, after step xiii), the third photoresist layer (17);

xv) selectively removing, after step xiv), a part of the second seed layer (14) that is unprotected by said at least one hinge member (3);

xvi) removing, after step xv), the first photoresist layer (12); and

xvii) removing, after step xvi), the first seed layer (11) and another part of the second seed layer (14) unprotected by said at least one support member (4) for defining a cavity (7) between the microplatform (2) and the base member.

9. The process for making the microdevice (1) according to claim 8, wherein step c) further comprises the step of polishing an upper surface (19) of the microplatform (2) after step xiii).

10. The process for making the microdevice (1) according to claim 3, wherein step c) comprises the steps of:

i) covering a side of the sacrificial substrate (20) with a first seed layer (21);

ii) covering the first seed layer (21) with a first photoresist layer (22); and

iii) photolitographically patterning the first photoresist layer (22) to produce an opening (23) on the first photoresist layer (22), the microplatform (2) being selectively electroformed in the opening (23) of the first photoresist layer (22).

11. The process for making the microdevice (1) according to claim 10, wherein step d) comprises the steps of:

iv) covering, after step iii), said side with a second seed layer (25);

v) covering, after step iv), said side with a second photoresist layer (26);

vi) photolitographically patterning the second photoresist layer (26) to produce at least one opening (27) on the second photoresist layer (26) that is aligned with the microplatform (2); and

vii) selectively electroforming said at least one hinge member (3) in said at least one opening (27) of the second photoresist layer (26).

12. The process for making the microdevice (1) according to claim 11, wherein step b) comprises the steps of:

viii) removing, after step vii), the second photoresist layer (26);

ix) covering, after step viii), said side with a third photoresist layer (28);

x) photolitographically patterning the third photoresist layer (28) to produce at least one opening (29) on the third photoresist layer (28), said at least one support member (4) being selectively electroformed in said at least one opening (29) of the third photoresist layer (28);

xi) selectively electroforming, after step x), of a soldering material (30) on said at least one support member (4);

xii) removing, after step xi), the third photoresist layer (28);

xiii) removing, after step xii), a part of the second seed layer (25) unprotected by said at least one support member (4) and hinge member (3);

xiv) removing, after step xiii), the first photoresist layer (22); and

xv) removing, after step xiv), the first seed layer (21) for separating the sacrificial substrate (20) from the microplatform (2).

13. The process for making the microdevice (1) according to claim 12, wherein step a) comprises the steps of:

xvi) providing a substrate (5) after step xv);

xvii) connecting, after step xvi), at least one electrode (6) and at least one contact pad (8) onto a side of the substrate (5);

xviii) covering the side of said substrate (5) with a protective layer (9);

xix) providing at least one opening (10) in the protective layer (9) for accessing said at least one contact pad (8); and

xx) soldering, after step xix), said at least one support member (4) onto the base member, via the soldering material (30) and said at least one contact pad (8).

14. A microdevice (1) comprising:

a base member;

at least one support member (4) mountably connected to the base member, said at least one support member (4) being selectively electroformed according to a selective electroforming process;

at least one hinge member (3) mountably connected to said at least one support member (4); and

a microplatform (2) hingedly connected to said at least one hinge member (3) for allowing relative movement of the microplatform (2) with respect to said at least one support member (4), the microplatform (2) being selectively electroformed according to a selective electroforming process.

15. The microdevice (1) according to claim 14, wherein the base comprises:

a substrate (5);

at least one electrode (6) and at least one contact pad (8) connected onto the substrate (5); and

a protective layer (9) covering the substrate (5) and said at least one electrode (6).

16. The microdevice (1) according to claim 15, wherein the substrate (5) is made from a glass, a ceramic plate or a semiconductor wafer and the protective layer (9) is made of SiO₂ or Si₃N.

17. The microdevice (1) according to claim 14, wherein said at least one hinge member (3) is selectively electroformed according to a selective electroforming process.

18. The microdevice (1) according to claim 17, wherein said at least one hinge member (3) is made of a material having low Young'"'"'s modulus, high yield strength and relatively low stiffness.

19. The microdevice (1) according to claim 14, wherein said at least one support member (4) is made of a material having high Young'"'"'s modulus and low density.

20. The microdevice (1) according to claim 14, wherein the microplatform (2) is made of a material having high Young'"'"'s modulus and low density.