Electrical contactor especially wafer level contactor using...

Details Electrical contactor especially wafer level contactor using... Electrical contactor especially wafer level contactor using...

1999-08-17

2002-10-22

Patel, Tulsidas (Department: 2839)

Electrical connectors

Having retainer or passageway for fluent material

For urging contact toward or away from mating contact

Reexamination Certificate

active

06468098

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to interconnect assemblies and methods for making and using interconnections and more particularly to interconnect assemblies for making electrical contact with contact elements on a substrate such as a semiconductor integrated circuit. More particularly, the present invention relates to methods and assemblies for making interconnections to semiconductor devices to enable test and/or burn-in procedures on the semiconductor devices.
BACKGROUND OF THE INVENTION
There are numerous interconnect assemblies and methods for making and using these assemblies in the prior art. For example, it is usually desirable to test the plurality of dies (integrated circuits) on a semiconductor wafer to determine which dies are good prior to packaging them and preferably prior to being singulated from the wafer. To this end, a wafer tester or prober may be advantageously employed to make a plurality of discreet pressure connections to a like plurality of discreet contact elements (e.g. bonding pads) on the dies. In this manner, the semiconductor dies can be tested prior to singulating the dies from the wafer. The testing is designed to determine whether the dies are non-functional (“bad”). A conventional component of a wafer tester or prober is a probe card to which a plurality of probe elements are connected. The tips of the probe elements or contact elements make the pressure connections to the respective bonding pads of the semiconductor dies in order to make an electrical connection between circuits within the dies and a tester such as an automated test equipment (ATE). Conventional probe cards often include some mechanism to guarantee adequate electrical contact for all contact elements at the bonding pads of the die regardless of the length of the contact elements or any variation in height between the two planes represented by the surface of the die and the tips of the probe pins or contact elements on the probe card. An example of a probe card having such a mechanism can be found in probe cards from FormFactor of Livermore, Calif. (also see the description of such cards in PCT International Publication No. WO 96/38858).
One type of interconnect assembly in the prior art uses a resilient contact element, such as a spring, to form either a temporary or a permanent connection to a contact pad on a semiconductor integrated circuit. Examples of such resilient contact elements are described in U.S. Pat. No. 5,476,211 and also in co-pending, commonly-assigned U.S. Patent Application entitled “Lithographically Defined Microelectronic Contact Structures,” Ser. No. 09/032,473, filed Feb. 26, 1998, and also co-pending, commonly-assigned U.S. Patent Application entitled “Interconnect Assemblies and Methods,” Ser. No. 09/114,586, filed Jul. 13, 1998. These interconnect assemblies use resilient contact elements which can resiliently flex from a first position to a second position in which the resilient contact element is applying a force against another contact terminal. The force tends to assure a good electrical contact, and thus the resilient contact element tends to provide good electrical contact.
These resilient contact elements are typically elongate metal structures which in one embodiment are formed according to a process described in U.S. Pat. No. 5,476,211. In another embodiment, they are formed lithographically (e.g. in the manner described in the above-noted patent application entitled “Lithographically Defined Microelectronic Contact Structures”). In general, resilient contact elements are useful on any number of substrates such as semiconductor integrated circuits, probe cards, interposers, and other electrical assemblies. For example, the base of a resilient contact element may be mounted to a contact terminal on an integrated circuit or it may be mounted onto a contact terminal of an interposer substrate or onto a probe card substrate or other substrates having electrical contact terminals or pads. The free end of each resilient contact element can be positioned against a contact pad on another substrate to make an electrical contact through a pressure connection when the one substrate having the resilient contact element is pressed towards and against the other substrate having a contact element which contacts the free end of the resilient contact element. Furthermore, a stop structure, as described in the above noted application Ser. No. 09/114,586, may be used with these resilient contact elements to define a minimum separation between the two substrates.
FIG. 1
shows one technique for the use of an interconnect assembly. This interconnect
101
includes a chuck structure
117
disposed above a semiconductor wafer
111
, which wafer is supported by a bellows structure
103
. The chuck structure is rigid (not deformable), and the surface of the chuck
117
which includes the contact elements
125
and
127
is also rigid. The bellows structure
103
includes an expandable bellows
105
and intake and outtake ports
107
A and
107
B. In one use of this bellows structure, a fluid, such as water
106
is passed into and out of the bellows structure
103
. A thin steel membrane
109
is welded or otherwise attached to the bellows
105
. The thin membrane may be used to exert uniform pressure against the back of wafer
111
to press the top surface of the wafer against the stop structures
121
and
123
, thereby causing electrical connections between the springs (or other resilient contact elements) on the wafer and the contact elements on substrate
117
. This uniform pressure may overcome some variations in flatness between the meeting surfaces, such as the top surface of the wafer
111
and the surface supporting the stop structures
121
and contact elements
125
and
127
. This thin steel membrane
109
also allows for the transfer of heat to or from the semiconductor wafer
111
which is disposed on top of the membrane
109
. The fluid such as water
106
, may be introduced into the bellows structure under pressure to force the membrane
109
into direct contact with the backside of the wafer
111
.
This fluid may be heated or cooled in order to control or affect the temperature of the wafer. For example, in a burn-in test of an integrated circuit (or wafer containing integrated circuits), the fluid may be heated to raise the temperature of the wafer and then cooled, and this process may be repeated over several cycles. The chuck
117
includes stop structures
121
and
123
which are proximally adjacent to contact elements
125
and
127
respectively. It may be desirable to place a thermal transfer layer between the membrane
109
and the back of the wafer
111
to improve the heat transfer efficiency between the fluid and the wafer
111
. The contact elements
125
and
127
are designed to make contact with the resilient contact elements
115
and
113
on the wafer
111
. It will be appreciated that there will typically be many more resilient contact elements and many more contact elements than those shown in FIG.
1
. The chuck
117
includes wiring or other interconnection in order to connect resilient contact elements
115
and
113
, through contact elements
125
and
127
, to a tester allowing communication of power, signals, and the like between the tester and the semiconductor wafer. The chuck
117
may be held in place by a post
118
in order to allow the wafer
111
to be pressed against the chuck
117
by the expanding of the bellows
105
; alternatively, the chuck
117
may be pressed and held by a clamshell support which contacts and covers the top of the chuck
117
with a backing plate and may also surround the sides and bottom of the bellows
105
.
FIG. 2
shows another example of an interconnect assembly
201
. In this case, a rigid chuck
203
supports a wafer of semiconductor devices
204
. The wafer includes a plurality of contact elements, such as the contact element
210
A which are designed and disposed to make contact relative to resilient contact elements on the wiring substrate
206
. The resili

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