JPH06310576A - Z-axis wiring for burn in of discrete die for non- packaged die - Google Patents

Abstract

PURPOSE: To provide a burn-in/test fixture where an individual die composed of two parts is reuseable by establishing contact between a bonding pad and an external connector lead by utilizing a Z axis anisotropic conductive wiring material and a TAB tape. CONSTITUTION: A TAB tape 41 is used to extend between a contact pad 37 on a die cavity plate 13 and a bonding pad 27. A Z axis anisotropic conductivity wiring material 53 is used to provide an interface between a bonding pad 27 and the TAB tape 41, and the TAB tape 41 and the bonding pad 27 are brought into ohmic contact therebetween through the Z axis anisotropic conductive wiring material 53 rather than directly. The Z axis anisotropic conductive wiring material 53 can extend between the TAB tape 41 and the contact pad 37 whereby connection of the TAB tape 41 to the contact pad 37 is facilitated. Thus, the die 21 can be burned in without bonding of a conductor to the bonding pad 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device electrical test apparatus. More specifically, the present invention relates to apparatus and methods that utilize conductive polymers and are used to perform dynamic burn-in and all electrical / performance / speed testing of discrete non-packaged or semi-packaged dies.

[0002]

2. Description of the Related Art In order to guarantee the quality and reliability of semiconductor devices,
Subjected to a series of test operations. This test operation typically involves a "probe test", in which individual dies on the wafer are first tested for function and speed. A probe card is used to electrically test the die at that level. The electrical connections interface with only one die on the wafer at a time and are not designed to interface with individual die. If the wafer has a functional die yield that indicates that the functional die is likely to be of good quality, each individual die is assembled in a package to form a semiconductor device. Packaging typically includes a leadframe and a plastic or ceramic housing. The packaged device is then subjected to another series of tests, including burn-in and individual tests. Individual testing allows the device to be tested for possible speeds and errors after assembly and after burn-in. Burn-in is a high temperature device (UU
Electrically activating T) accelerates the failure mechanism. This eliminates potential failures that would otherwise occur.

Due to these variants of operation, devices, eg memory boards, assembled on a circuit arrangement can be burned in along the memory boards to be distributed to the devices in order to guarantee the reliability of the circuit. . With this closed asse-mbly testing, it is conceivable that the devices will be individually packaged for easier operation. It is proposed that the composite integrated circuit device be packaged as a single unit. This can be accomplished with or without a conventional leadframe. This has two problems compared to conventional test methods. First, individual testing is more difficult because regular leadframe packages are not used.
Moreover, when multiple devices are assembled in a single package, the performance of the package degrades to that of the die with the worst performance. In other words, the ability to sort individual die is limited to that obtained by probe testing. Secondly, packaging has other limitations, which are weighted by burn-in stress conditions and packaging 7
Is the limiting factor for the burn-in test.

A hybrid integrated circuit form incorporates multiple dies in a single package. This increases packaging density and allows matched members on different dies to be packaged as a single item. The non-defective rate of such an assembled product is at least the product of the non-defective rate of the die of the constituent member, which results in a lower total non-defective rate. Considering the performance of the die,
The non-defective rate tends to be significantly lower than the product of the non-defective rate of the constituent members. If the test results of the burned-in die are available, the yield rate of the component can be increased. In addition, components can be tailored by matching various characteristics (eg, signal timing and response time), thereby providing more margin for the response inherent in a complete assembly. Such hybrid integrated circuits require the semiconductor die to be burned in. It would be desirable to be able to test individual die in a manner similar to that achieved with individually packaged semiconductor devices.

General Assigned US Pat. No. 4,899,1
At 07, a reusable burn-in / test fixture for individual TAB (tape automated bonding) dies is provided. This fixture consists of two parts,
One is a die cavity plate for housing the semiconductor die as the unit under test (UUT), and the other establishes electrical contact with the die and the burn-in oven. The first part of the test fixture contains a cavity in the side up of the circuit into which the die is inserted. The die remains on the floating platform. The second portion has a substrate with a high embrittlement temperature, and the corresponding die pad probe is mounted thereon. Each of the plurality of probes is connected to an electrical trace on a substrate (similar to a PC board) and each die pad of each die is electrically isolated from each other for high speed functional testing. The probe tips are arranged in an array to accommodate 8 or 16 dies. The two parts of the test fixture are bonded so that each pad on each die is aligned with the corresponding probe tip. The test fixture is shaped to accommodate 8 or 16 dies to maximize the efficiency of the functional tester. When singulating parts (separating into individual dies), there are several tests and associated operations. For this reason, it is inconvenient to keep multiple dies in a single test fixture.

TAB tapes are typically bonded with bond pads to establish long-term reliable electrical connections without the application of external pressure to the assembly. Bonding the TAB tape establishes a mechanical connection that allows the bond pad to lift off (become in a detached form) from the die when the TAB tape is removed. Bonding pads are conductive areas on the surface of the die that are used as wiring to connect the circuit components on the die to the outside world. Typically, the conductor is bonded to the bond pad, but electrical contact can be established through the bond pad by biasing the conductor against the bond pad without actually bonding. One of the problems encountered in non-packaged die burn-in and all characterization tests is the physical stress caused by the connection of bond pads to external connection circuitry. This problem is complicated by the fact that in many die geometries the bond pads fit below the surface level of the passivation layer. The passivation layer is a layer of low eutectic glass, such as BPSG, applied to the die to protect the circuit components on the die.

[0007]

It has been found desirable to perform testing and related operations on individual fixtures prior to final assembly. To achieve this,
A reusable burn-in / test fixture for a separate two-piece die is provided. This fixture is composed of two parts, one of which is a die cavity plate for accommodating a semiconductor die as a unit under test (UUT). The Z-axis anisotropic conductive wiring material is used to establish ohmic contact with the bonding pads on the semiconductor die or equivalent bonding points. Z-axis anisotropic conductive wiring materials are also known as isotropically conductive materials. The Z-axis anisotropically conductive wiring material can be sufficiently aligned with the die shape at the bond pads to establish ohmic contact without substantially damaging the bond pads. The contact can be established by the bias force, allowing the die to be burned in and tested without bonding the conductor to the bond pad. Z-axis anisotropic conductive wiring materials are metal-filled polymer composites that can serve as compliant wiring materials for connectors and test applications. This material is an elastomeric conductive polymer wire.
rconnect; ECPI) belongs to a material group called materials. These are AT & TBeII Research Institute or shin Ets
u Available from Polymer America.

In the first aspect, the die is placed face up in the cavity of the first portion of the fixture. The TAB tape is used to carry signals between the bonding pad locations on the fixture and the external connector leads. The TAB tape establishes contact with the external connector leads or other leads on the fixture leading to the external connector leads. Z-axis anisotropic conductive wiring material is placed between the die and the TAB tape at the bond pad location to establish contact between the bond pad and the TAB tape. Therefore, the contact between the bonding pad and the external connector lead is established by utilizing the Z-axis anisotropic conductive wiring material and the TAB tape. The Z-axis anisotropic conductive wiring material and the conductors on the TAB tape extend from the bonding pads to the connection points, and the connection points lead to the contacts, which in turn lead to the external connector leads.

The Z-axis anisotropically conductive wiring material and TAB tape are essentially similar to conventional TAB wiring methods except that their connecting function can be accomplished without permanently bonding the TAB tape to the die. is there. To maintain contact with the circuit components on the die, the Z-axis anisotropic conductive wiring material and TAB tape are biased against the die when the burn-in / test fixture is assembled. Non-bonding contacts of Z-axis anisotropic conductive wiring material and TAB tape are mainly applied to the die pad. The contact between the tape and the other conductor may also be a non-bonding contact. Bonding the TAB tape to the fixture may also be done without permanent bonding or by bonding techniques. The Z-axis anisotropic conductive wiring material is biased against the die by a separate compressible elastomer pad or the elastomeric properties of the Z-axis anisotropic conductive wiring material.

In a preferred form of this aspect, the external connector leads are preferably DIP (dual inline package) or QFP.
(Quad flat pack) shaped connector pins. The pin terminates at the connection point. In another form of this aspect, the conductors on the TAB tape extend to the top of the tape, and the bonding of the second portion of the fixture causes an electrical connection between the conductor and the external connection lead through the second portion or a separate conductor. Is established.
The fixture establishes electrical contact with the single die and the burn-in oven, and also allows testing of individually packaged forms of the die. In a second aspect of the invention, a reusable burn-in / test fixture for a two-part individual die is provided. The first portion of the test fixture contains a cavity into which the die is inserted circuit side up. The die remains on the floating platform. The second portion has a probe for each die pad. Each probe is connected to an electrical connector that can be used for bonding to a burn-in board and for connecting to an individual circuit tester. The Z-axis anisotropic conductive wiring material is placed directly against the bond pads to establish the interface between the probe and the die. Advantageously, the probe exerts a pressure on the Z-axis anisotropically conductive wiring material, which establishes a good ohmic contact with the bonding pad.

The probe can take several forms. The vapor-deposited conductor is similar to the use of TAB tape except that it can be located on a fixed substrate. A conductive elastomer may be used, in which case the conductive elastomer cooperates with the Z-axis anisotropic conductive wiring material to bias the Z-axis anisotropic conductive wiring material against the bonding pads. Alternatively, a biased metal probe, such as a probe wire, may be used which biases the Z-axis anisotropically conductive wiring material against the bonding pad. Can cooperate with. In a third aspect, the die is placed face up in the cavity of the first portion of the fixture. The second portion of the fixture contains the external connector leads and is used to establish contact with the bond pads on the die. Adhesion of the die to the external connection leads is through a contact point on the second portion through the Z-axis anisotropic conductive wiring material, or an intermediate such as TAB tape where contact is established with the Z-axis anisotropic conductive wiring material. Established through members. In a fourth aspect, the die is placed facedown on a fixture that includes the die receiving cavity. The Z-axis anisotropic conductive wiring material is placed in the die receiving cavity below the die, and contact with the bonding pads on the die is established through the Z-axis anisotropic conductive wiring material using the external connector leads on the fixture. To be done. In this aspect, the probe, Z-axis anisotropic conductive wiring material and electrical connector are located on the second portion. In a preferred form of this aspect, the electrical connector extends upwardly from the circuit side face of the die so that the fixture is normally faced down on the integrated circuit side of the die and connected to the tester.

Referring to FIGS. 1 and 2, the burn-in fixture 11 of the present invention includes a die cavity plate 13 and a cover 15. The die cavity plate 13 includes a die receiving cavity 17. The die-accommodating cavity 17 has a size sufficient to accommodate at least the die 21. The die 21 is connected at bond pads 27, which are typically 0.1 mm wide. The die cavity plate 13 has slots 31 which allow easy access to the bottom of the die 21 as the die is lifted from the die receiving cavity 17. Alignment of the die 21 in the die cavity plate 13 is achieved by aligning the cover 15 with the bonding pads 27. A plurality of external connector leads 33 extend from the burn-in fixture 11. As can be seen in FIG. 2, in the preferred embodiment, the external connector leads 33 are adhered to and extend from the die cavity plate 13. The external connector leads 33 are shown as connector pins and are preferably DIP or QFP shaped. The external connector lead 33 is fixed by the die cavity plate 13, and is terminated on the die cavity plate 13 by the contact pad 37. The contact pad 37 is aligned with the bonding pad 27 in a generally planar manner.

Referring to FIGS. 1 and 2, TAB tape 41 is used to extend between contact pads 37 and bond pads 27 on die cavity plate 13. As shown in FIG. 4, the bond pads are typically recessed below the top level 43 established by the BPSG passivation layer 45. The TAB tape 41 comprises a plastic film 47, preferably molded from polyamide, on which a plurality of conductive traces 49 are formed. With further reference to FIG. 2, the conductive traces 49 are bumps 5 provided for alignment with the bonding pads 27 or contact pads 37.
1, 52. Therefore, the conductive traces 49 can carry signals between the bond pads 27 and the contact pads 37, and also bond pads 27.
And contact pad 37 and respective bumps 51,
Ohmic contact is established with 52. The formation of ohmic contact between the bumps 52 and the contact pads 37 requires applying a biasing force to the contact pads 37 sufficient to move the TAB tape 41.

In some cases, bond pad 27 is recessed below the top surface of the die as a result of the application of passivation layer 45. Bonding pad 27 also tends to be brittle. The Z-axis anisotropic conductive wiring material 53 is used to provide an interface between the bonding pad 27 and the TAB tape 41. This makes T
Ohmic contact is made through the Z-axis anisotropic conductive wiring material 53 rather than directly between the AB tape 41 and the bonding pad 27. Conveniently, the Z-axis anisotropically conductive wiring material can also extend between the TAB tape 41 and the contact pads 37, thereby allowing the TAB tape 4 to move.
The connection to the contact pad 37 of No. 1 becomes easy. The use of Z-axis anisotropically conductive wiring material 53 between the bonding pad 27 and the TAB tape 41 serves several functions. Due to the elastically deforming ability of the Z-axis anisotropic conductive wiring material, it can be deformed sufficiently to reach into the recess defined by the bonding pad 27. Due to the client nature, ohmic contact with the bonding pad 27 is possible with minimal damage to the bonding pad. This is important in non-packaged die burn-in and testing, as it is desirable that the bond pads remain substantially undamaged after burn-in and testing. Due to the compliant nature of the Z-axis anisotropically conductive wiring material 53, intermediate contact members such as TAB tape 41 may be slightly misaligned with bonding pads 27. As long as there is a sufficient amount of material in the conductive path under the TAB tape 41 that also contacts the bonding pad 27, ohmic contact is established. It is also necessary to apply a biasing force to maintain ohmic contact. The biasing force may be achieved by using another elastomer pad, but the biasing force may also be provided by the elastomeric nature of the Z-axis anisotropically conductive wiring material 53.

The Z-axis anisotropic conductive wiring material 53 need not be permanently bonded to the bonding pad 27. Ohmic contact is established by the bias force. This allows the die 21 to move to Z without breaking the bonding pad 27.
The axially anisotropic conductive wiring material 53 and the TAB tape 41 can be lifted. Therefore, the Z-axis anisotropic conductive wiring material 53 and the TAB tape 41 are bonded to the bonding pad 2.
Signals can be transmitted between the contact pads 7 and the contact pads 37. Further, the Z-axis anisotropic conductive wiring material 53 and the TAB tape 41 can be permanently bonded to the die 21 to maintain the adhesion of the TAB tape 41 to the die 21 after burn-in. The cover 15 includes a rigid cover plate 61 and an elastic compressible elastomeric strip 63 that optionally acts as an elastic biasing member.
When the cover plate 61 is fixed to the die cavity plate 13, the elastomer strip 63 biases the Z-axis anisotropic conductive wiring material 53 and the TAB tape 41 with respect to the die 21. This establishes an ohmic contact between the bonding pad 27 and the conductive trace on the TAB tape 41 without bonding the TAB tape 41 to the bonding pad 27. The optimal technique for temporarily fixing the die 21 in the die cavity plate 13 is to use a pre-cured RTV silicone strip, commonly known as a "gel pack", as the backing strip 65. . The backing strip 65 has sufficient electrostatic charge and coefficient of friction to hold the die in place without adhesive,
It is also elastomeric. In other words, the silicone holds the silicon in place and the silicone is
B tape 41 and cover plate 61 are biased.

It has been found that the best technique for temporarily fixing the die 21 in place in the die cavity plate 13 is to use a pre-cured RTV silicone strip as the backing strip 65. Elastomeric strip 63 is considered optional. Thus, the use of backing strip 65 biases die 21 against TAB tape 41 without the use of elastomeric strip 63.
However, the distance is chosen to be suitable for biasing. Non-bonding contact of the Z-axis anisotropic conductive wiring material 53 on the bonding pad 27 is important. T
The contact between the AB tape 41 and the contact pad 37 on the fixture 11 can be made by a bonding technique. It is expected that such bonding will not deteriorate the fixture 11 even if the fixture is used many times. When bonding is used for such contact, the conductor from the TAB tape remains with the fixture 11, but the operation of the fixture 11 is not hindered.

Positioning pins 67 are used to align the cover plate 61 with the die cavity plate 13. The clamp 71 fixes the cover plate 61 at a predetermined position on the die cavity plate 13. The clamp 71 can be constructed with a wire clasp, which is positioned to latch as shown, or fitted in a horizontal position on the die cavity plate 13 and cover plate 61. With the cover plate 61 in place, the conductors on the TAB tape 41 extend from the bonding pads 27 to the contact pads 37, so that the bonding pads 27 are electrically connected to the external contact leads 33. FIG. 5 shows a modification of the embodiment of FIGS. 1 and 2 in which the cover plate 81 modified to establish contact with the Z-axis anisotropic conductive wiring material 53 in the area of the bonding pad 27 uses an intermediate contact 83. Contact with the external connector leads 33 is established by electrical contacts 85 on the cover plate 81. This contact may be by a Z-axis anisotropically conductive wiring material 53, a conductive polymer or a direct metal-to-metal connection.

FIG. 6 shows an embodiment in which the die cavity housing 91 has an intermediate contact 93. The die 21 is placed face down and the connection between the bonding pad 27 and the intermediate contact 93 is established. In this case, the Z-axis anisotropically conductive wiring material 53 is below the die 21. A pre-cured RTV silicone backing strip 95 is used to secure the die 21 to the cover plate 97 and bias the die 21 against the intermediate contact 93. In another embodiment of the package 101, as shown in FIG. 7, the die housing 103 is used to hold the die 21, and the upper portion 105 uses the external connector pins 107 to test the die 21 externally. Used to connect to circuit components. The die receiving housing 103 contains a die receiving cavity 109, which supports the die 21 in alignment with electrical contacts 111 which align with the bonding pads 27 on the die 21. The Z-axis anisotropic conductive wiring material 53 is located between the die 21 and the upper portion 105, and the electrical connection is established between the bonding pad 27 and the contact 111 using the connector pin 107.
In one aspect of this configuration, the contact 111 is a metal compound. Other conductors may be used as the contact 111. As an example, a conductive polymer can be used as the contact 111.

In the embodiment as shown in FIG. 8, the contact pin 123 extends to the Z-axis anisotropic conductive wiring material 53 at the position of the bonding pad 27 on the die 21. The contact pins 123 are mounted on the insulating cover 125, and the cover 125 is mounted on the die cavity housing 1.
When mounted on 31, an electrical connection is established between the contact pin 123 and the base portion 127 of the external connector pin 129. In some cases, an elastomeric strip 135 may also be used on the top surface to further secure the die 21 in place in the housing 131. The contact 123 is a pin type contact similar to the probe contact. Due to the relatively accurate alignment of the cover 125 with the die 21, the contacts 123 remain relatively strong while maintaining sufficient force to establish good ohmic contact with the Z-axis anisotropically conductive wiring material 53 with the bonding pads 27. It can be designed to have a low bias force. FIG. 9 shows a configuration in which the housing fixture 141 simply holds the die 21 and is in electrical communication with the TAB tape 143. The TAB tape 143 is the fixture 14
It extends beyond region 1 and terminates in an external connector 147. The Z-axis anisotropic conductive wiring material 53 is located between the TAB tape 143 and the die 21 and establishes contact with the die pad 27. Although the detailed location of the bond pads has not been described, various geometries can be tested, including, for example, conventional placement of bond pads at the ends of die 21. The invention may also be used to test LOC (Ieads over chip) or other shaped die. In each of the above examples, the assembled fixture is fitted in conventional test equipment such as a burn-in oven.

[0020]

The present invention provides a reusable burn-in / test fixture for a two-part individual die. The fixture of the present invention establishes electrical contact with the burn-in oven and individual die tester.

[Brief description of drawings]

FIG. 1 is a diagram showing a preferred embodiment of a burn-in fixture of the present invention.

FIG. 2 is a diagram showing a preferred embodiment of the burn-in fixture of the present invention.

FIG. 3 is a detailed view of a Z-axis anisotropic conductive wiring material and TAB tape used as one embodiment of the present invention.

FIG. 4 is a detailed cross-sectional view of a Z-axis anisotropic conductive wiring material and a TAB tape.

FIG. 5 is a diagram showing a modification of the first and second aspects in which the modified cover plate is an intermediate contact member.

FIG. 6 shows how the die cavity housing is used for the connection between the die and the external connection pins.

FIG. 7 illustrates another embodiment of a test package whose top is used to connect the die to external test circuit components.

FIG. 8 shows a variation of the embodiment of FIGS. 1 and 2 in which the deformed cover plate has probe wire contact.

FIG. 9 illustrates a variation of the invention in which a flexible tape and Z-axis anisotropic conductive wiring material are used to directly connect the die to an external connector that connects to an external test circuit component.

FIG. 10 is a diagram showing a modified example of the present invention.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor David A. Henbury, Smouk Ranch Drive, Boyes, 83709, Idaho, United States, 10855 (72) Inventor Warren M. Fernworth, Bo Bo, 83709, Idaho, United States Ease, West Columbia Road 10781

Claims (9)

[Claims] 1. a) a first plate; b) a die receiving cavity on the first plate; c) a second plate which engages with the first plate; d) first and second plates having a plurality of contacts thereon. One; e) a plurality of contacts that are placed so that when the die is placed in the die receiving cavity, the contacts are aligned with the contact locations on the die; f) electrically conductive in the Z-axis, which is perpendicular to the pad surface. A pad placed on the die between the die and the plurality of contacts and providing electrical isolation across the pad surface; and g) electrically connected to the contact and mounted on one of the plates. An individual test apparatus for testing a semiconductor integrated circuit device in a die form including a connector terminal. 2. A) cooperating with the pad, biasing a die housed in a die receiving cavity having a contact after the first and second plates are mated, and the pad and the contact location on the die. An elastomer strip away from the pad that provides sufficient pressure between the pad and the contact location on the die to establish an ohmic contact; and b) further electrostatic attraction and friction forces to the die-accommodating cavity. Fixing the die in position within the die, thereby placing the die in the die receiving cavity and the second plate
The individual testing device of claim 1, further comprising an elastomeric strip capable of maintaining the die in positional alignment with the die receiving cavity before being mated with the plate. 3. A biasing die contained in a die receiving cavity having contacts after the first and second plates are mated and biased in cooperation with the pad to provide the pad and the contact location on the die. The individual test device of claim 1, further comprising means remote from the pad for providing sufficient pressure between the pad and the pad to establish an ohmic contact between the pad and the contact location on the die. 4. The die receiving cavity further has a biased substrate therein, the biased substrate exerts a biasing force on the die, the biasing force passing through the pad and the contact location on the die and the plurality of die. The individual test device of claim 1, which cooperates with the pad to establish an electrical connection with a contact. 5. The contact further includes a contact member that is aligned with the die receiving cavity after the first and second plates are mated, the contact member cooperating with the pad and the pad and the die on the die. An individual test apparatus as claimed in any one of claims 1, 2 or 4 wherein sufficient pressure is provided between the pad and the contact location to establish ohmic contact between the pad and the contact location on the die. 6. The method of claim 1, 2 or 4 wherein the contact further comprises a flexible rod extending into the die receiving cavity after the first and second plates are mated.
Individual test equipment described. 7. The individual test device of claim 1, wherein the contacts further each include a contact pad that is aligned with the die receiving cavity after the first and second plates are mated. 8. The plurality of contact positions are in electrical communication with the connector terminals when the first and second plates are secured together with the die in the die receiving cavity. The individual test apparatus according to item 1. 9. The connector further comprises: the first plate and the second plate being aligned by the aligning means, and the connector terminal being aligned with the contact position on the die when the die and the insulating substrate are placed in the die receiving cavity. The individual test apparatus according to claim 1, 2 or 4, wherein the terminal is placed on the second plate.