Source: http://www.google.com/patents/US7910460?dq=patent:3079728
Timestamp: 2014-03-12 01:14:42
Document Index: 277865509

Matched Legal Cases: ['application No. 2008100824576', 'Application No. 2007', 'application No. 200910225920', 'application No. 10', 'application No. 2007', 'application No. 2007']

Patent US7910460 - Metallic electrode forming method and semiconductor device having metallic ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA metallic electrode forming method includes: forming a bed electrode on a substrate; forming a protective film with an opening on the bed electrode to expose the bed electrode from the opening; forming a metallic film covering the protective film and the opening; mounting the substrate on an adsorption...http://www.google.com/patents/US7910460?utm_source=gb-gplus-sharePatent US7910460 - Metallic electrode forming method and semiconductor device having metallic electrodeAdvanced Patent SearchPublication numberUS7910460 B2Publication typeGrantApplication numberUS 12/805,537Publication dateMar 22, 2011Filing dateAug 5, 2010Priority dateMar 6, 2007Also published asDE102008012678A1, DE102008012678B4, US7800232, US20080217771, US20100311191Publication number12805537, 805537, US 7910460 B2, US 7910460B2, US-B2-7910460, US7910460 B2, US7910460B2InventorsManabu Tomisaka, Hisatoshi Kojima, Akihiro NiimiOriginal AssigneeDenso CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (21), Non-Patent Citations (6), Referenced by (2), Classifications (37) External Links: USPTO, USPTO Assignment, EspacenetMetallic electrode forming method and semiconductor device having metallic electrodeUS 7910460 B2Abstract A metallic electrode forming method includes: forming a bed electrode on a substrate; forming a protective film with an opening on the bed electrode to expose the bed electrode from the opening; forming a metallic film covering the protective film and the opening; mounting the substrate on an adsorption stage, and measuring a surface shape of the metallic film by a surface shape measuring means; deforming the substrate by a deforming means so that a difference between the principal surface and a cutting surface is within a predetermined range; measuring a surface shape of the principal surface, and determining whether the difference is within a predetermined range; and cutting the substrate along with the cutting surface so that the metallic film is patterned to be a metallic electrode.
1. A metallic electrode forming method for a semiconductor device comprising:
forming a bed electrode on a principal surface of a semiconductor substrate, wherein the bed electrode is electrically connected to a semiconductor element; forming a protective film on the bed electrode, and
forming an opening in the protective film so that the bed electrode is exposed from the opening;
forming a metallic film on the protective film to cover the protective film and the opening of the protective film;
mounting the semiconductor substrate with the metallic film on an adsorption stage, and measuring a surface shape of at least a part of the metallic film by a surface shape measuring means, wherein the adsorption stage adsorbs and fixes the semiconductor substrate on the stage, and wherein the part of the metallic film is disposed on the protective film;
deforming the semiconductor substrate based on a surface shape data of the part of the metallic film by using a deforming means capable of displacing the semiconductor substrate so that a difference between the principal surface of the semiconductor substrate and a cutting surface is within a predetermined range, and wherein the deforming means is disposed on a stage side;
measuring a surface shape of the principal surface of the semiconductor substrate, and determining whether a difference between the cutting surface and the principal surface of the semiconductor substrate is within a predetermined range; and
cutting the semiconductor substrate with the metallic film along with the cutting surface so that the metallic film is patterned to be a metallic electrode when the difference between the cutting surface and the principal surface of the semiconductor substrate is within the predetermined range.
wherein, in the cutting the semiconductor substrate with the metallic film, only a part of the metallic film remains in the opening of the protective film so that the part of the metallic film provides the metallic electrode.
wherein the deforming means is disposed on a backside of the adsorption stage so that the deforming means is opposite to the semiconductor substrate, and wherein the deforming means displaces the semiconductor substrate via the adsorption stage.
wherein the deforming means includes a plurality of actuators, and
wherein each actuator independently displaces the semiconductor substrate.
wherein each actuator is a piezoelectric actuator having a piezoelectric element.
wherein the surface shape measuring means measures the surface shape of the metallic film at a plurality of measurement points, and
wherein the number of measurement points is larger than the number of actuators.
wherein the deforming means displaces the semiconductor substrate in such a manner that the deforming means applies displacement to the semiconductor substrate at a plurality of displacement points, each of which corresponds to the measurement point.
wherein the surface shape measuring means is a laser displacement gauge, which scans the surface shape of the metallic film along with a plane parallel to the cutting surface.
9. A metallic electrode forming method for a semiconductor device comprising:
forming a bed electrode on a principal surface of a semiconductor substrate, wherein the bed electrode is electrically connected to a semiconductor element;
forming a protective film on the bed electrode, and forming an opening in the protective film so that the bed electrode is exposed from the opening;
mounting the semiconductor substrate on a first adsorption stage to contact the metallic film on the first adsorption stage, wherein the first adsorption stage includes a first flat surface for adsorbing the semiconductor substrate thereon;
arranging the semiconductor substrate over a third adsorption stage in such a manner that the backside surface faces the third adsorption stage, arranging a displacing means under the third adsorption stage in such a manner that the displacing means is opposite to the semiconductor substrate, and applying displacement to the third adsorption stage so that the third adsorption stage fits and contacts the backside surface of the semiconductor substrate; and
adsorbing and fixing the backside surface of the semiconductor substrate on the third adsorption stage, and cutting the semiconductor substrate with the metallic film so that only a part of the metallic film remains in the opening of the protective film, wherein the part of the metallic film provides a metallic electrode.
wherein the displacing means includes a plurality of actuators, and wherein each actuator is capable of controlling the displacement independently.
wherein each actuator is a piezoelectric actuator including a piezoelectric element. Description
CROSS REFERENCE TO RELATED APPLICATIONS This application is a Divisional Application of allowed U.S. patent application Ser. No. 12/073,166, filed on Feb. 29, 2008 now U.S. Pat. No. 7,800,232 which is based on Japanese Patent Applications No. 2007-55982 filed on Mar. 6, 2007, No. 2007-194016 filed on Jul. 26, 2007, No. 2007-222762 filed on Aug. 29, 2007 and No. 2007-337039 filed on Dec. 27, 2007, the disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION The present invention relates to a metallic electrode forming method and a semiconductor device having a metallic electrode.
BACKGROUND OF THE INVENTION In recent years, there has been a demand for inexpensive formation of metallic electrodes, which are used for solder joint or the like, on a circuit surface formed on a semiconductor substrate.
SUMMARY OF THE INVENTION In view of the above-described problem, it is an object of the present disclosure to provide a metallic electrode forming method. It is another object of the present disclosure to provide a semiconductor device having a metallic electrode.
Alternatively, the first blade portion may be connected to the second blade portion with a predetermined arc having a curvature radius defined as R, the cutting tool cuts the protective film with a cutting depth defined as d, and the predetermined pitch defined as P has a relationship of 0<P≦2/3(2Rd−d2)1/2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Referring to the drawings, the first embodiment of a metallic electrode forming method for semiconductor devices and a semiconductor device in accordance with the present invention will be described below. FIG. 1 is a sectional explanatory view of a semiconductor device having metallic electrodes formed thereon according to the metallic electrode forming method of the first embodiment. FIG. 2A to FIG. 4B show steps included in the metallic electrode forming method. FIG. 5A and FIG. 5B are explanatory views of a surface shape control apparatus. FIG. 5A is a sectional view, and FIG. 5B is a plan explanatory view of the surface shape control apparatus seen from a semiconductor substrate side. FIG. 6A to FIG. 6C are explanatory diagrams presenting an example of surface shape control for the semiconductor substrate. FIG. 6A is a profile of thicknesses of the semiconductor substrate detected during adsorption, FIG. 6B is a profile of displacements applied by a deformation unit, and FIG. 6C is a profile of thicknesses of the semiconductor substrate displaced by the deformation unit. FIG. 7 is a sectional explanatory view of the semiconductor device whose metallic electrodes are soldered.
A semiconductor device 10 to be adapted to a power card or the like is formed with a semiconductor substrate 11, which is made of silicon or the like, as a body. Bed electrodes 12 that are element electrodes are formed on the principal side 11 a of the semiconductor substrate 11 using pure aluminum (Al) or an aluminum alloy such as an aluminum-silicon (Al�Si) alloy or an aluminum-silicon-copper (Al�Si�Cu) alloy.
Metallic electrodes 15 to which wires are coupled are formed to cover both the surfaces 12 a of the bed electrodes 12 bared through the respective openings 13 a and the flanks 13 c of the protective film 13 creating the level difference. The metallic electrodes 15 are formed using a titan (Ti)-nickel (Ni)-gold (Au) laminate or a Ni�Au laminate whose components are layered in that order on the sides of the bed electrodes 12, and are electrically connected to the respective bed electrodes 12.
Thereafter, as shown in FIG. 2B, a metallic film 14 is formed to cover each of the bed electrodes 12, the top 13 b of the protective film 13, and the flanks 13 c of the protective film 13 according to a plating method dr sputtering method. The metallic film 14 may be a laminate such as a Ti�Ni�Au laminate or a Ni�Au laminate or may be a uni-laminar metallic film.
When the piezoelectric actuators 24 a generate upward displacements, the upward displacements are applied to the semiconductor substrate 11 via the adsorption stage 21 b. Consequently, the semiconductor substrate 11 is deformed. The piezoelectric actuators 24 a apply displacements to the semiconductor substrate 11 via the adsorption stage 21 b. Therefore, such an event can be prevented that a stress is locally exerted in the semiconductor substrate 11 by the piezoelectric actuators 24 a and causes the semiconductor substrate 11 to locally deform.
Second Embodiment The second embodiment of a metallic electrode forming method for semiconductor devices and a semiconductor device in accordance with the present invention will be described below with reference to the drawings. Herein, a description will be made on the assumption that Au electrodes are adopted as electrodes which bring power elements such as bipolar transistors or transverse diffusion transistors (LDMOS) into contact with an external substrate. FIG. 8A to FIG. 10 are sectional explanatory diagrams concerning an electrode forming method for semiconductor devices of the second embodiment.
Thereafter, a protective film 53 made of silicon nitride (P�SiN) is formed on the tops of the bed electrodes 12, and openings 53 a through which parts of the bed electrodes 12 are bared are formed from the surface of the protective film 53 toward the bed electrodes 12.
Third Embodiment Referring to the drawings, the third embodiment of a metallic electrode forming method for semiconductor devices in accordance with the present invention will be described below. FIG. 1 is a sectional explanatory view of a semiconductor device having metallic electrodes formed according to the metallic electrode forming method of the third embodiment. FIG. 13A to FIG. 15B show steps included in the metallic electrode forming method. FIG. 16A and FIG. 16B are explanatory views presenting a variant of a method of pouring a filler for formation of a flat portion.
A semiconductor device 10 adapted to a power card or the like is formed using a semiconductor substrate 11, which is made of silicon or the like, as a body. Bed electrodes 12 that are element electrodes are formed on the principal side 11 a of the semiconductor substrate 11 using pure aluminum (Al) or an aluminum alloy such as an aluminum-silicon (Al�Si) alloy or an aluminum-silicon-copper (Al�Si�Cu) alloy.
Metallic electrodes 15 to which wires are coupled are formed to cover the surfaces 12 a of the bed electrodes 12 bared through the respective openings 13 a. The metallic electrodes 15 are formed using a titan (Ti)-nickel (Ni)-gold (Au) laminate or a Ni�Au laminate whose components are layered in that order on the sides of the bed electrodes 12, and are electrically connected to the respective bed electrodes 12.
Thereafter, as shown in FIG. 13B, a metallic film 14 is formed to cover both the bed electrodes 12 and the protective film 13 according to a plating method or sputtering method. The metallic film 14 may be a laminate such as a Ti�Ni�Au laminate or a Ni�Au laminate or may be a uni-laminar metallic film.
At the step of forming the flat portion 216, a method of applying the filler to the reference surface 226 a of the flattening stage 226, and pressing the flattening stage against the back side 11 b may be adopted in order to pour the filler to the gap. In this case, even when a material that is too viscous to readily invade into the gap is adopted, the filler can be reliably poured into the gap between the reference surface 226 a and the back side 11 b. Fourth Embodiment The fourth embodiment of a metallic electrode forming method for semiconductor devices in accordance with the present invention will be described with reference to drawings. FIG. 17A and FIG. 17B are explanatory views of a displacement control adsorption apparatus employed in the metallic electrode forming method of the fourth embodiment. FIG. 17A is a sectional view, and FIG. 17B is a plan explanatory view of the displacement control adsorption apparatus seen from a semiconductor substrate side. FIG. 18A and FIG. 19B show steps included in the metallic electrode forming method of the fourth embodiment.
A depressurization hole 221 f through which the adsorption unit 22 is connected and the displacement unit 223 are formed in or disposed on the lower stage 221 c. In the present embodiment, multiple piezoelectric actuators 223 a are adopted as the displacement unit 223. The piezoelectric actuators 223 a are arranged in the form of a lattice with a predetermined space, for example, a space of 1 cm between adjoining ones. The piezoelectric actuators 223 a are abutted on the back side 221 g of the adsorption stage 221 b and disposed so that they can generate upward displacements. FIG. 17A and FIG. 17B are concerned with a case where sixteen piezoelectric actuators 223 a are, for convenience' sake, arranged in total in four columns and four rows. The piezoelectric actuators 223 a can generate mutually different displacements that can be mutually independently controlled by the control computer 25. The displacements generated by the respective piezoelectric actuators 223 a can be highly precisely controlled, the backlash made by the piezoelectric actuators 223 a is limited, and the amount of heat dissipated from the piezoelectric actuators 223 a during operation is small.
Fifth Embodiment Referring to the drawings, the fifth embodiment of a metallic electrode forming method for semiconductor devices in accordance with the present invention will be described below.
A semiconductor device 10 adapted to a power card or the like is formed using a semiconductor substrate 11, which is made of silicon or the like, as a body. Bed electrodes 12 that are element electrodes are formed on the substrate side 11 a (i.e., principal side) of the semiconductor substrate 11 using pure aluminum (Al) or an aluminum alloy such as an aluminum-silicon (Al�Si) alloy or an aluminum-silicon-copper (Al�Si�Cu) alloy.
Thereafter, as shown in FIG. 20B, a metallic film 14 is formed to cover both the bed electrodes 12 and the protective film 13 according to a plating method or sputtering method. The metallic film 14 may be a laminate such as a Ti�Ni�Au laminate or a Ni�Au laminate or may be a uni-laminar metallic film.
Cq 2 =Cu 2 +qu 2 (1) R 2=(R−d)2 +D 2 (2)
Within the area, in an area where the metallic film 14 is layered on the protective film 13, the metallic film 14 restricts deformation of swarf, and the protective film 13 is plucked. Assuming that a point of intersection between a perpendicular extended from the point q1 and an arc q2-r2 is a point v, the area where the protective film 13 is plucked is indicated with an arc q2-v.
On the other hand, when the protective film 13 alone is cut, once an appropriate cutting condition is designated, a smooth cut plane on which a mean of roughness levels at ten points is 0.1 μm or less can be provided.
q1q2=q2u2−q2q1 (4)1/2P=D−P (5)
P=2/3D (6)
0<P≦2/3(2Rd−d 2)1/2 (7)
0<P≦2/3(2Rd−d 2)1/2 Consequently, the surface roughness of the protective film 13 having undergone cutting work can be diminished.
Sixth Embodiment The sixth embodiment of a metallic electrode forming method for semiconductor devices in accordance with the present invention will be described below with reference to the drawings. FIG. 24 is a sectional explanatory diagram concerning the states of the metallic electrode and protective film cut by the cutting tool employed in the metallic electrode forming method in accordance with the sixth embodiment.
Consequently; the maximum cut width D2 is expressed by an equation (9) below using the angle θ and depth d.
Similarly to the fifth embodiment, since a relationship expressed by 0<P≦2/3D2 should merely be satisfied, the pitch P should merely satisfy the relationship provided by an expression (10) below.
When the cutting tool 331 having the edge of the distal part of the cutting face 331 a thereof formed like an isosceles triangle whose sides having an equal length form an angle θ with respect to the metallic film 14 is employed, if the pitch P is designated so that the relationship provided below will be established among the angle θ, the cut depth d in the protective film 13, and the pitch P, an area where the protective film 13 whose surface is plucked to intensify the surface roughness is bared can be cut during cutting to be performed after the cutting tool 331 is moved by the designated pitch P.
0<P≦2/3(2Rd−d 2)1/2 When the cutting tool having the first and second blade portions thereof shaped to form a continuous arc having the radius of curvature R is employed, when the pitch is designated so that the relationship expressed below will be established among the radius of curvature R, the cut depth d in the protective film, and the pitch P, the surface roughness of the protective film having undergone cutting work can be diminished.
0<P≦2/3(2Rd−d 2)1/2 Alternatively, the cutting tool may have the first and second blade portions thereof shaped to tilt by an angle θ with respect to the surface of the metallic film; and the pitch is designated so that a relationship expressed below will be established among the angle θ, the cut depth d in the protective film caused by the cutting tool, and the pitch P.
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