JP2672972B2 - Semiconductor wafer inspection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a semiconductor wafer inspection apparatus (prior art). In a semiconductor manufacturing process, a temperature environment in which these semiconductors are used is assumed. However, it is necessary to perform the temperature characteristic test and the environmental characteristic test in the wafer state.

Also, in recent years, supercomputers have become larger and larger,
The speeding up is progressing, and the semiconductor chips are also required to have high integration and speeding up. Along with this, the amount of power consumption per unit area of the semiconductor chip is also increasing and the amount of heat generation is also increasing. Therefore, each chip is housed in a package having a cooling unit before being mounted on a computer.

However, in the wafer state, the temperature of the semiconductor chip rises during the inspection process, and if it is significant, there is a risk of burning the semiconductor chip. Therefore, it is necessary to cool the mounting body and inspect it under the same conditions as when mounting the computer.

In order to carry out these inspections, a mechanism for cooling a wafer mounted on a mounting body has been developed and put into practical use.

FIG. 5 illustrates a mechanism for cooling a wafer of a conventional probe device.

The probe device (1) includes a mounting body (3) which is movable in a planar direction on a base (2), and a head plate (4) which is arranged in parallel with a space above the mounting body (3). And a cooling circulation system (5) for cooling the surface of the mounting body (3).

Therefore, the probe device (1) drives the pump (6) of the cooling circulation system (5) which communicates with the mounting body (3) to circulate and cool the pump.

Then, the semiconductor wafer (7) (hereinafter abbreviated as a wafer) is mounted on the cooled mounting body (3) and inspected.

(Problem to be Solved by the Invention) However, in the conventional probe apparatus (1), the air in the vicinity is rapidly cooled by radiative cooling from the cooled stage (3). This chilled air causes condensation on the stage (3).

The condensed water droplets are further cooled and changed into a frost state to freeze the mounting body (3).

Even if the wafer (7) is mounted on the frozen mounting body (3), the wafer (7) cannot be mounted in close contact with the mounting body (3), the cooling conductivity deteriorates, and the set cooling cannot be performed. There was a drawback.

Further, since the frost generated on the mounting body (3) solidifies the mounted wafer (7), it was difficult to separate the wafer (7) during transportation.

Therefore, the object of the present invention is made in view of the above-mentioned conventional problems, by controlling the mounting body on which the inspection object is placed to a desired temperature, the electrical characteristics of the inspection object. An object of the present invention is to provide a semiconductor wafer inspection apparatus capable of inspecting a semiconductor wafer.

[Configuration of the invention]

(Means for Solving the Problem) In the present extermination, in a semiconductor wafer inspection apparatus that inspects the electrical characteristics of a semiconductor wafer, a mounting body on which the semiconductor wafer is mounted and the mounting body are cooled. Cooling means, a block provided in the flow path of the cooling liquid supplied from this cooling means, and a detection means for detecting light that is incident on the surface of this block and frost generated on the surface of the block by the reflected light And a control means for controlling the cooling means by a program stored in advance based on the signal detected by the detection means.

Further, the block has a smaller volume than the mounting body described above.

Therefore, according to the present invention, by making the block smaller in volume than the mounting body, the block is cooled faster than the mounting body and frost is generated quickly, so that the frost generated on the surface of the block is detected by the detection means. By detecting
The cooling means can be controlled before frost is formed on the mounting body.

(Embodiment) One embodiment in which the device of the present invention is applied to a low temperature wafer prober (hereinafter abbreviated as a prober) that performs disconnection, short circuit, and other electrical inspections in a state where the semiconductor wafer is cold during the semiconductor wafer manufacturing process. Examples will be described with reference to the drawings.

The external structure of the prober of this embodiment will be described with reference to FIG.

The prober (8) substantially air-tightly surrounds the probe device by the enclosing means (9) to allow a dry gas to flow into a space that is shielded from the atmosphere to cool the mounting body, and to cool the mounting body. A wafer is placed, and the wafer is cooled and inspected by heat conduction for inspection.

The prober (8) is roughly classified into a loader section (10) for wafer transfer, an inspection section (12) for inspecting electrical characteristics by bringing a probe card (11) into contact with an electrode of the wafer, and a wafer is placed thereon. It is composed of a mounting part (Fig. 3).

In the loader section (10), the inspection section (12) and the placing section (FIG. 3) are arranged so that the loader section (10) has a side surface of the inspection section (12) as shown in FIG. , For example, they are arranged in parallel on the right side surface. The mounting part (13) is provided on the base (14) surface of the inspection part (12) so as to be movable in two axial directions, and the wafer (15) is mounted on the top surface of the mounting part (13). It is arranged to be placed.

The loader section (10) is a cassette (16) in which a plurality of wafers (15) provided on the right side surface of the inspection section (12) are stacked stepwise at regular intervals, for example, φ100 mm.
25 wafers (15) are taken out from a cassette (16) containing 25 sheets and transferred by a rotating arm (17) to a mounting section (13) on the inspection section (12) side.

In this transfer, the rotating arm (17) rotates from the loader section (10) side to the inspection section (13) side and is placed above the placing section (13). The wafer (15) is transferred from the rotating arm (17) by a pin projecting from the mounting body (18) arranged on the top surface of the mounting portion (13).

The inspection unit (12) has a head plate (19) parallel to the base (14) on a pillar erected from the laid base (14).
Is covered.

This head plate (19) has probe stylus (20)
Are provided so as to contact the electrodes of the wafer (15) mounted on the top surface of the mounting body (18).

The placing section (13) is provided on the laid base (14) so as to be biaxially driven so as to be horizontally moved by a moving means, for example, a rail and a bearing.

Further, a single shaft that can be driven to move up and down is provided above the two shafts.

At the upper part of this uniaxial shaft, a θ rotating part is provided which can rotate in the horizontal direction.

 Here, the θ rotation portion is referred to as a mounting body (18).

The placing body (18) is provided with a cooling circulation system (21) for cooling.

As shown in FIG. 1, the cooling circulation system (21) is provided outside with a heat exchanger, for example, a heat exchange jacket (not shown) embedded in the hollow portion of the mounting body (18). It is connected by a cooling tank (22) and a flexible tube (23).

Here, the circulation of the cooling liquid is performed by driving the pump (24).

In such an apparatus, the wafer (15) is cooled and heated,
In order to contact the probe stylus (20) and inspect the electrical characteristics of the wafer (15), frost may be generated as the temperature is lowered, even if a dry gas is flowing in. (15) In order to prevent the formation of frost on top, it is necessary to always feel the cold temperature before the formation of frost and prevent the formation of frost.

That is, it is necessary to sense the cooling temperature at which frost is generated on the mounting body (18) and to make the dry humidity more than the humidity of the dry gas, or to implement a means such as stopping the pump supplying the cooling liquid. is there.

The characteristic configuration of this embodiment is that the mounting body (1
8) The cooling unit for cooling is provided, and after detecting the frost generated in this cooling unit, the pump or the like supplying the cooling temperature is stopped.

The cooling means includes a cooling section (25) cooled by the mounting body (18), a detection section for detecting the presence or absence of frost on the top surface of the cooling section (25), and a detection section for detecting the frost. And a control unit for stopping rotation of the pump (24) based on the frost information.

The cooling unit (25) circulates a cooling liquid, for example, ethylene glycol, through the heat exchange jacket and the container (26) for cooling the mounting body (18) so that the temperature becomes lower than that of the mounting body (18). It is configured.

If the cooling unit (25) is cooled, the smaller the volume is, the better if the flow rate and flow velocity of the cooling liquid circulated in the mounting body (18) are constant,
The block joint (25
a) into the flow inlet of the above-mentioned mounting body (18) with a nipple joint (2
It is fixed so as to pass through the block joint (25a) and is fed to the heat exchange jacket.

The block joint (25a) is connected to the inside of the container (26) through the elbow (25c) and the pump (24) from the orthogonal ends of the block joint (25a), and the cooling liquid (27) in the container (26) is passed through the block joint (25). The pump (24) is circulated so as to cool the mounting plate (18) and the mounting body (18).

The drive of this pump (24) is controlled by the CPU (28).

Here, the block joint (25a) is the mounting body (1
A mirror surface (29) is provided on the same surface as the surface of 8) so that the occurrence of frost can be easily detected.

Next, the detecting means (30) for detecting the frost generated on the mirror surface (29) will be described.

The detection means (30) is provided on the bottom surface of the head plate (19) so as to face the mirror surface (29).

The detecting means (30) is configured such that the beam emitted from the light emitting section (31) of the detecting means (30) is incident on the light receiving element (32).

Here, if there is no frost on the mirror surface (29), the light on the light receiving element (32) side is reflected by the reflection on the mirror surface (29) as a frost-free signal.
The CPU (28) is making the decision.

Further, as shown in FIG. 2, when the frost is generated, the mirror surface (29) causes the reflected light to be reflected by the frost (29a).
Since it is not incident on 2), the CPU (28) judges that there is frost (29a) and stops the pump (24) that is back-flowing the cooling liquid, or the program is programmed beforehand to adjust the flow rate. It is designed to be stored.

 Next, the operation will be described.

The wafer (15) taken out from the cassette (16) is transferred to the mounting body (18) on the inspection section (12) side, and the inspection section (12) is transferred.
A dry gas is caused to flow into the enclosure space of (1), and a cooling liquid, for example, ethylene glycol, is circulated from the container by a pump (24) to the heat exchange jacket of the mounting body (18).

 Next, the characteristic operation of this embodiment will be described.

The cooling liquid (27) is sent to the inner space of the block joint (25a) by the pump (24), and then to the heat exchange jacket in the inner space of the mounting body (18) in this order in the container (26). Circulate inside.

When frost starts to form on the mirror surface (29) of the block joint (25a) while the mounting body (18) is being cooled to the set temperature, the light emitting section (31) provided on the surface opposite the mirror surface (29). ) Beam is not incident on the light receiving element (32) side due to the frost.

Then, the CPU (28) senses that frost has occurred, and mounts the pump (24) supplying the cooling liquid (27) on the mounting body (18).
It is possible to inspect the wafer (15) from the block joint (25a) without generating frost on the mounting body, which is controlled so that the cooling does not proceed.

In the above, the relay block (32) in which the relay block (32) is arranged between the block joint (25a) and the pump (24).
Is for adjusting the length of the flexible tube (23) when the mounting body (18) moves in the plane direction.

〔The invention's effect〕

The present invention, by entering light on the surface of the block, detecting the frost generated on the surface of the block by the reflected light, by controlling the cooling means by a program stored in advance based on the detected signal, Since the temperature can be controlled before frost is generated on the mounting body, it is possible to inspect the electrical characteristics of the semiconductor wafer in a state where frost is not generated on the mounting body.

Further, by making the block smaller in volume than the mounting body, the block is cooled faster than the mounting body and frost is generated quickly, so that the frost generated on the surface of the block is detected by the detection means, The cooling means can be controlled before the frost is generated on the placement body.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view for explaining a characteristic structure of a cryogenic probe device of the present invention, and FIG. 2 is a frost generated on a mirror surface of a block joint provided on the mounting body of FIG. Explanatory diagram for explaining the state of
FIG. 3 is an explanatory diagram for explaining the arrangement of the entire configuration of FIG. 1, FIG. 4 is an external configuration diagram of a low temperature wafer prober of one embodiment of the low temperature probe device of the present invention, and FIG. 5 is a conventional probe device. It is an explanatory view explaining. 25a …… Block joint, 29 …… Mirror surface 29a …… frost, 30 …… Detecting means 31 …… Light emitting part, 32 …… Light receiving element

Claims (2)

(57) [Claims] 1. A semiconductor wafer inspection apparatus for inspecting the electrical characteristics of a semiconductor wafer, comprising: a mounting body on which the semiconductor wafer is mounted; cooling means for cooling the mounting body; and a supply from the cooling means. The block provided in the flow path of the cooling liquid to be detected, the detection means for detecting the frost generated on the surface of the block by the light incident on the surface of this block, and the signal detected by this detection means An inspection apparatus for a semiconductor wafer, comprising: a control means for controlling the cooling means by a program stored in advance based on the above. 2. The semiconductor wafer inspection apparatus according to claim 1, wherein the block has a smaller volume than the mounting body.