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GB2210200A - Semiconductor contact arrangements - Google Patents

Semiconductor contact arrangements Download PDF

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Publication number
GB2210200A
GB2210200A GB8828998A GB8828998A GB2210200A GB 2210200 A GB2210200 A GB 2210200A GB 8828998 A GB8828998 A GB 8828998A GB 8828998 A GB8828998 A GB 8828998A GB 2210200 A GB2210200 A GB 2210200A
Authority
GB
United Kingdom
Prior art keywords
contact
area
stud
wafer
hole
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8828998A
Other versions
GB2210200B (en
GB8828998D0 (en
Inventor
C V H Miles
P L T Bishop
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Mobility Ltd
Original Assignee
Westinghouse Brake and Signal Co Ltd
Westinghouse Brake and Signal Holdings Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB8728878A external-priority patent/GB8728878D0/en
Application filed by Westinghouse Brake and Signal Co Ltd, Westinghouse Brake and Signal Holdings Ltd filed Critical Westinghouse Brake and Signal Co Ltd
Priority to GB8828998A priority Critical patent/GB2210200B/en
Publication of GB8828998D0 publication Critical patent/GB8828998D0/en
Publication of GB2210200A publication Critical patent/GB2210200A/en
Application granted granted Critical
Publication of GB2210200B publication Critical patent/GB2210200B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
    • H01L23/482—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of lead-in layers inseparably applied to the semiconductor body (electrodes)
    • H01L23/4821—Bridge structure with air gap
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H01L24/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L24/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L2224/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
    • H01L2224/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
    • H01L2224/13001—Core members of the bump connector
    • H01L2224/13099—Material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/45001—Core members of the connector
    • H01L2224/45099—Material
    • H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45117—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 400°C and less than 950°C
    • H01L2224/45124—Aluminium (Al) as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/00014—Technical content checked by a classifier the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01013—Aluminum [Al]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01015—Phosphorus [P]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01033—Arsenic [As]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01074—Tungsten [W]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1301—Thyristor

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Die Bonding (AREA)
  • Testing Or Measuring Of Semiconductors Or The Like (AREA)

Abstract

The contact arrangement comprises a semiconductor wafer 1 having on one of its major faces 9 an area 4 of one type of conductivity and an electrical contact 11 in face-to-face engagement with that area, in which the contact is located with respect to that area and is secured to the wafer by a stud 15 welded to the wafer and projecting into a hole 14 extending through the contact. The stud may comprise an aluminium ball which is deformed by welding to secure the contact to the wafer. To prevent a preferential electrical path through the weld, the stud may be surrounded by an insulating sleeve. <IMAGE>

Description

Semiconductor Contact Arrangement This invention relates to contact arrangements for semiconductor devices.
As is well known, semiconductor devices comprise a wafer of semiconductor material on the opposed major faces of which emerge zones of differing-type conductivity as areas of conductivity-type. Th se areas are a face-to-face engagement with generally-planar shaped contacts. The sandwich thus formed by the wafer contact assembly is then encapsulated in a housing. However, prior to encapsulation, the sandwich, of necessity, has to be handled for a variety of treatments including ultimately, encapsulation.
The conductivitywtype areas of semiconductor wafers have become of ever more sophisticated shape to achieve required characteristics of the ultimate device. With this increasing sophistication of shape of the wafer areas, the associated contact has, necessarily, also become of increasing sophistication of shape with resultant problems of orientation and location of the contact relative to the area to avoid short-circuiting of the P-n junction defined by the area. These problems are the more great with the more complex devices such as thyristors, transistors and GTO devices.
In spite of this increasing sophistication over the past decades and the attendant problems of relative location, the securing in position of a contact when properly located relative to its associated area has traditionally and by all seiconductor manufacturersr been achieved by glueing the contact to the wafer with rubber/resin glues and many such glues have been tried.
However, these glues can creep between the contact and the wafer - preventing subsequent effective electrical connection - and, at least with certain glues they can affect the lifetime of the device.
It is not feasible to weld the contacts in position for the weld would provide a preferential electrical path which would negate the whole purpose of an area contact which is to ensure spread of the current through the area/contact over substantially the whole of the face-to-face engaged area.
The present invention seeks to overcome the problems inherent in the traditional method of securing contacts to the wafer.
Accordingly, the present invention provides a semiconductor contact arrangement comprising a semiconductor wafer having on one of its major faces an area of one type of conductivity and an electrical contact in face-to-face engagement with that area, in which the contact is located with respect to that area and is secured to the sandwich by a stud welded to the wafer and projecting into a hole extending through the contact from the face thereof engaged with the wafer.
The stud may be encircled by a sleeve of electrically insulating material whereby the stud is electrically insulated from the contact.
Conveniently, the stud may have been formed from a ball of material weldable to the area of the sandwich, the ball having been previously positioned in the hole and the ball in the subsequent welding of it to the area forming the stud.
Where the stud is encircled by a sleeve of electrically insulating material whereby the stud is electrically insulated from the contact, the sleeve may be button-shaped and secured to the area of the sandwich by the stud extending through the hole, The sleeve may have therein more than a single hole and the stud then be constituted by a length of wire which passes through two of the holes in the sleeve and is welded to the area of the area of the sandwich at each end of the length of wire, Alternatively, the stud may have a head and a shank, the head being larger in cross-sectional area than the shank The hole in the contact may be formed by etching of the contact during or after the shaping of the contact or by machining.
Embodiments of the present invention will now be described in greater detail, by way of example only, with reference to the accompanying drawing of which; Fig. 1 shows a cross-sectional view of a part of a semiconductor sandwich and Figs. 2 to S show fragmentary cross-sectional views on an enlarged scale of alternative constructions for locating and securing the contact to the wafer.
Referring, firstly, to Fig. 1, the semiconductor wafer 1 incorporates P and N regions 2, 3 and 4 between which are PN junctions 5 and 6. The edge 7 of the wafer 1 is chamfered and then covered by electrical insulating material 8.
The regions 4 terminate on the upper major face 9 of the wafer 1 in areas 10.
A contact 11 is mounted on the upper face 9 of the wafer 1. The lower face 12 of the contact 11 is mesa-etched to provide areas 13 of the contact 11 which are of complementary shape and similar size to the areas 10 of the face 9 of the wafer 1.
The contact 11 is provided with two or three (of which one only is shown) holes 14. It will be noted that these holes 14 are conical-shaped with the smaller diameter being at the end of the hole adjacent the wafer 1, Positioned in the hole 14 is an aluminium ball 15.
The contact 11 is secured to the wafer 1 and its areas 13 held correctly located with respect to the areas 10 of the wafer 1, by welding the ball 15 to the area 10.
In the course of so welding, the ball 15 will be formed into a stud which will, at least in part, take up the shape of the hole 14. The stud thus formed will both secure the contact 11 to the wafer 1 and keep it properly aligned with respect thereto. The thus-assembled sandwich will be readily handleable without risk of the contact 11 being disturbed relative to the wafer 1 and the sandwich can be further treated as may be necessary and can be encapsulated in conventional ways.
It will be noted that welding of the ball 15 to the wafer 1 will ensure that the thus-formed stud does not stand proud of tho top surface of the contact 11.
Thus, in encapsulation, the surface of the housing contact engageable with the top surface of contact 11 can be planar.
It may be found that the ball 15 when deformed by welding to form the stud does not make sufficiently good electrical connection with the contact 11 as to provide an unacceptably-good preferential electrical path as seriously to affect the operating characteristics of the ultimate device, If so, then plain aluminium ball can be used Should this not be so and a plain aluminium ball does provide such an unacceptably-good preferential path, then a sleeve of insulating material can be positioned between the ball 15 and the hole 14.
In an alternative, instead of the ball 15, there may be used a short length of aluminium wire. In this case, any necessary electrical insulation of the formed stud from the contact 11 may be provided either by a sleeve of insulating material encompassing the aluminium wire or by an insulating coating on the wire.
In the first illustrated alternative construction shown in Fig. 2, the ball 15 is enclosed in an electsically-insulating sleeve 20 as suggested above.
In Fig. 1, the hole 14 was of conical shape and may have been formed by machining. In Fig. 2, the hole 14 has been formed at the same time as the shaping of the contact 11 by etching from both sides of the contact 11. The thus-formed hole 14 will have a shape somewhat as illustrated - in particular, a shape which will cause the sleeve 20 when deformed by the welding of the ball 15 to the wafer 1 to form the stud, to hold the contact 11 against moement relative to the wafer 1, In the Fig. 3 alternative, the hole 14 has been formed by etching from the top side only of the contact 11 thus forming a generally bowl-shaped hole. In this alternative, the sleeve 20 is generally button-shaped with a single central hole 30. Through the hole 30 was inserted a short length of aluminium wire which was subsequently welded to the wafer 1 at 31.In so doing, a head 32 was formed on the thus-formed stud, the head 32 being of greater cross-section than the shank 33 and thus fixing the sleeve 20 to the wafer 1.
In Fig. 4, the sleeve 20 is again button-shaped but in this alternative, the sleeve 20 has a pair of holes 40.
In this case, the stud was formed by welding each end 41 of a length of aluminium wire 42 to the wafer 1, the wire bridging that part of the sleeve 20 between the two holes 40. In this alternative, the hole 14 has again been formed by etching in from both sides of the contact 11. Thus, in welding the wire 42 to the wafer 1, the sleeve 20 will be deformed to grip the wall of the hole 14 and thus firmly locate the contact 11 on the wafer 1.
In Fig. 5, the hole 14 has been shaped by machining to provide a shoulder 50. In this case, the stud 15 initially had ahead 51 and a shank 52 - the head 51 being of greater cross-sectional dimensions than the shank 52. The sleeve 20 is of complementary shape to the stud 15. Thus, when the stud 15 is welded by the lower end of its shank 52 to the wafer 1, the head 51, through the sleeve 20, will engage the shoulder 50 in the hole 14 and, again, serve to secure the contact 11 on the wafer 1.
Clearly, there are many other alternative constructions than those here illustrated and described and many other alternative shapes of and methods of forming a suitable stud.
Further, the stud may be pre-welded to the wafer 1. In this case, the contact 11 would later be positioned on the wafer 1 - the pre-welded stud then acting to locate the wafer. After location of the contact, the stud could then be pressure-deformed to effect receiving of the contact 11 to the wafer 1.
In all of the above described embodiments, the stud is formed in the area of the wafer electrically to be contacted by the contact. However, the stud can equally well be provided in some other area of the wafer so long as the stud is electrically-insulated from the contact 11.

Claims (9)

Claims:
1. A semiconductor contact arrangement comprising a semiconductor wafer having on one of its major faces an area of one type of conductivity and an electrical contact in face-to-face engagement with that area, in which the contact is located with respect to that area and is secured to the sandwich by a stud welded to the wafer and projecting into a hole extending through the contact from the face thereof engaged with the wafer.
2. An arrangement as claimed in Claim 1, ~wherein the stud is encircled by a sleeve of electrically insulating material whereby the stud is electrically insulated from the contact.
3. An arrangement as claimed in either one of Claims 1 and 2, wherein the stud has been formed from a ball of material weldeable to the area of the sandwich, the ball having been previously positioned in the hole and the ball in the subsequent welding of it to the area forming the stud.
4. An arrangement as claimed in Claim 2, wherein the sleeve is button-shaped and is secured to the area of the sandwich by the stud extending through the hole.
5. An arrangement as claimed in Claim 4, wherein the sleeve has therein more than a single hole and the stud is constituted by a length of wire which passes through two of the holes in the sleeve and is welded to the area of the area of the sandwich at each end of the length of wire.
6. An arrangement as claimed in either one of Claims 2 and 4, wherein the stud has a head and a shank, the head being larger in cross-sectional area than the shank.
7, An arrangement as claimed in any one of the preceding claims, wherein the hole in the contact has been formed by etching of the contact during or after the shaping of the contact.
8. An arrangement as claimed in any one of Claims 1 to 6, wherein the hole in the contact has been formed by machining.
9. A semiconductor contact arrangement comprising a semiconductor sandwich having on one of its major faces an area of one type of conductivity and an electrical contact in face-to-face engagement with that area, wherein the contact is located with respect to that area and is secured to the sandwich by means substantially as herein described with reference to and as illustrated in any one of the Figures in the accompanying drawing.
GB8828998A 1987-12-10 1988-12-12 Semiconductor contact arrangement Expired - Lifetime GB2210200B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8828998A GB2210200B (en) 1987-12-10 1988-12-12 Semiconductor contact arrangement

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8728878A GB8728878D0 (en) 1987-12-10 1987-12-10 Semiconductor contact arrangement
GB8828998A GB2210200B (en) 1987-12-10 1988-12-12 Semiconductor contact arrangement

Publications (3)

Publication Number Publication Date
GB8828998D0 GB8828998D0 (en) 1989-01-25
GB2210200A true GB2210200A (en) 1989-06-01
GB2210200B GB2210200B (en) 1990-06-06

Family

ID=26293183

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8828998A Expired - Lifetime GB2210200B (en) 1987-12-10 1988-12-12 Semiconductor contact arrangement

Country Status (1)

Country Link
GB (1) GB2210200B (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1087688A (en) * 1966-09-30 1967-10-18 Standard Telephones Cables Ltd Improved method of semiconductor die soldering
EP0186818A2 (en) * 1984-12-31 1986-07-09 International Business Machines Corporation Chip to pin interconnect method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1087688A (en) * 1966-09-30 1967-10-18 Standard Telephones Cables Ltd Improved method of semiconductor die soldering
EP0186818A2 (en) * 1984-12-31 1986-07-09 International Business Machines Corporation Chip to pin interconnect method

Also Published As

Publication number Publication date
GB2210200B (en) 1990-06-06
GB8828998D0 (en) 1989-01-25

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19951212