JP2006214950A - Semiconductor chip, and inspection device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method for a semiconductor chip capable of applying nondestructive inspection, even in any semiconductor chip and even under a production, irrespective of a shape of a wiring pattern for a circuit. <P>SOLUTION: In this inspection method for the semiconductor chip 1 formed with a pn junction 6 for inspection in a portion other than an area of a wire 3 for a circuit, and formed with a wire 7 for the inspection for bringing both fellow electrode parts of the pn junction for the inspection into continuity, and having a midway of the wire for the inspection laid along the wire for a circuit, a laser beam R is emitted to the pn junction to generate an OBIC current I, a magnetic flux B generated in the periphery of the OBIC current is detected by a SQUID element 12, when the OBIC current flows in the wire for the inspection, and a detection distribution pattern of the magnetic flux detected by the SQUID element is compared with a reference distribution pattern of the magnetic flux preliminarily found in a normal case to detect the presence of a wiring defect in the semiconductor chip. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Conventionally, as a method for inspecting circuit wiring formed on a semiconductor chip, there is a method using a SQUID magnetometer (see, for example, Patent Document 1).
This is because the SQUID magnetometer detects the magnetic flux induced by the OBIC current generated when the pn junction whose both ends are short-circuited with a conductor is irradiated with a laser beam, so that leakage defects including short-circuit defects, disconnection defects, etc. This enables non-destructive inspection of wiring defects.
JP 2002-313859 A

  According to the above-described conventional configuration, since a pn junction formed as a circuit wiring is used in a semiconductor chip to be inspected, the inspection method cannot be used for those in which the pn junction is not originally formed, and the pn In the case where the junction is formed so as to overlap with another circuit wiring, the nondestructive inspection by the OBIC current generated by the laser light irradiation cannot be performed.

  Further, since the pn junction of the circuit wiring is used, the inspection method cannot be used until the circuit wiring is formed. Therefore, the inspection cannot be performed during the manufacturing.

  Therefore, in order to solve the above-described problems, the present invention provides a semiconductor chip to which a nondestructive inspection can be applied, and an inspection apparatus and an inspection method thereof, regardless of the type of semiconductor chip or in the course of manufacturing. With the goal.

In order to solve the above-described problems, the semiconductor chip of the present invention forms an inspection pn junction at a location other than the circuit wiring region of the substrate having a circuit wiring formed on the surface thereof. Form an inspection wiring that connects both electrode parts,
In addition, the inspection wiring is arranged along the circuit wiring in the middle.

A semiconductor chip inspection apparatus according to the present invention is the semiconductor chip inspection apparatus according to claim 1,
A laser irradiator for irradiating a pn junction for inspection with a laser beam;
A SQUID element for detecting a magnetic flux generated when the OBIC current generated in the inspection pn junction flows through the inspection wiring by the irradiation of the laser beam;
A wiring failure determination unit that compares the detected distribution pattern of the magnetic flux detected by the SQUID element with the reference distribution pattern of the magnetic flux obtained in the normal case to determine the presence or absence of wiring failure is provided. .

Furthermore, the semiconductor chip inspection method of the present invention is the semiconductor chip inspection method according to claim 1,
An OBIC current is generated by irradiating a pn junction for inspection of a semiconductor chip with laser light, and a magnetic flux generated around the OBIC current flowing through the inspection wiring is detected by a SQUID element.
In this method, the detection distribution pattern of the magnetic flux detected by the SQUID element is compared with the reference distribution pattern of the magnetic flux obtained in advance in the normal case to detect the presence or absence of wiring defects in the semiconductor chip.

  According to the configuration of the semiconductor chip described above, the inspection pn junction is arranged at a position other than the circuit wiring region. Therefore, unlike the conventional case, the inspection pn junction is not provided, that is, the pn junction formed in the circuit wiring is not provided. Unlike what is used, non-destructive inspection using laser light irradiation or the like can be performed in any wiring form.

  Further, according to the above inspection apparatus and inspection method, the OBIC current and the magnetic flux generated by the current are detected by the SQUID element by irradiating the inspection pn junction disposed at a position other than the circuit wiring region with the laser beam. As a result, the non-destructive inspection of the semiconductor chip is performed. Therefore, as compared with the conventional case where the circuit wiring itself is used for inducing the OBIC current, the circuit wiring in the middle of the manufacture of the semiconductor chip is also reduced. Wiring defects can be detected, and even when the circuit wiring itself does not have a pn junction, the inspection using the OBIC current can be performed, and therefore the applicable range of the semiconductor chip to be inspected is greatly increased.

[Embodiment]
Hereinafter, a semiconductor chip, an inspection apparatus and an inspection method thereof according to an embodiment of the present invention will be described.

  In the inspection according to the present invention, non-destructive inspection, that is, OBIC (induced by laser light irradiation) (irradiation of laser light) is used to determine whether or not there is a wiring defect (also a defect) such as disconnection or cracking of circuit wiring formed on a semiconductor chip. The determination is made by detecting an optical beam induced current (magnetic beam) current and a magnetic flux (magnetic field) generated by the OBIC current using a superconducting quantum interference device (SQUID).

First, a semiconductor chip to be inspected will be described with reference to FIG.
As shown in FIG. 1, the semiconductor chip 1 is provided with a wiring layer 4 in which a plurality of circuit wirings 3 (3A, 3B) are formed on one surface (lower surface in the drawing) of a silicon substrate 2, An electrode portion (also referred to as an electrode pad) 5 made of aluminum or the like is formed at the surface position of the end portion of each circuit wiring 3, and an inspection pn junction 6 is formed on the substrate 2 side. The inspection wiring (also referred to as a conductor) 7 that forms a closed circuit by connecting (short-circuiting) both electrode portions of the pn junction 6 is formed.

  The inspection pn junction 6 is in a region (location) other than the circuit wiring region (each circuit wiring 3 and each electrode portion 5, or at least each circuit wiring 3), in other words, in a plan view. More precisely, the projection units (projection patterns) are provided at positions where they do not overlap each other.

Further, an intermediate portion 7 a of the inspection wiring 7 connected to the inspection pn junction 6 is formed along (in parallel with) the predetermined circuit wiring 3.
The inspection pn junction 6 and the inspection wiring 7 are provided at a plurality of locations according to the position and the number of circuit wirings 3 to be inspected, and are provided at one location in FIG. Shows the case.

  Therefore, when the inspection pn junction 6 is irradiated with the laser beam R from the outside, an OBIC current I is induced to flow in the inspection wiring 7, and a magnetic flux (magnetic field) B is generated around the inspection wiring 7 by the OBIC current. Will occur. The magnetic flux B shown in FIG. 1 shows a normal case.

  FIG. 2 shows a specific example of a region other than the circuit wiring region (shown by hatching), that is, a region where the inspection pn junction is arranged. FIG. 2A shows a case where the semiconductor chip 1 is provided around the semiconductor chip 1, that is, outside the electrode portion 5. The outside of the electrode portion 5 is a region R other than the circuit wiring region. FIG. 2B shows a case where the semiconductor chip 1 is provided inside the semiconductor chip 1, that is, inside the electrode portion 5 [also shown in FIG. 2A]. This is a region R other than the circuit wiring region. In this case, the width D of the region R other than the circuit wiring region coincides with the laser spot diameter (for example, 3 μm or less is preferable in consideration of condensing convenience and workability).

Next, an inspection apparatus for inspecting the semiconductor chip 1 using a SQUID element will be briefly described.
As shown in FIG. 1, the inspection apparatus includes at least a laser oscillator 11 for irradiating a pn junction 6 for inspection from a side opposite to the wiring layer 4 of the semiconductor chip 1 with a laser beam having a predetermined wavelength, and this inspection. SQUID element 12 for detecting the magnetic flux B generated around the OBIC current generated in the pn junction 6 when flowing through the inspection wiring 7, and the detection distribution pattern of the magnetic flux detected by the SQUID element 12 And a reference distribution pattern of magnetic flux (which may be actually measured or numerical simulation) in the case of a normal semiconductor chip obtained in advance, and both distribution patterns By comparison, a wiring failure judgment unit (not shown) for judging the presence or absence of wiring failures such as disconnection and cracking is provided. The SQUID element 12 is attached to an inspection needle 13, and the inspection needle 13 is made of a high permeability alloy [for example, Permalloy (trade name)].

Here, laser light used for inspection will be described.
Examples of the laser light used include a He—Ne laser with a wavelength of 633 nm, a He—Ne laser with a wavelength of 1152 nm, a laser diode with a wavelength of about 1300 nm, and a YLF (Ilf) laser with a wavelength of about 1300 nm. It is used properly according to the.

  In addition, as a method for inspecting an IC chip having a pn junction, there is a method of measuring a terahertz electromagnetic wave generated from the IC chip by irradiating the pn junction with a femtosecond laser (terahertz electromagnetic wave method). As a laser light source in this case, an ultrashort light pulse having a wavelength in the range of 300 nm to 2 μm, a time average energy in the range of 0.1 mW to 10 W, and a pulse width in the range of 1 femtosecond to 10 picoseconds can be generated. A mode-locked titanium sapphire laser or femtosecond fiber laser is used.

When using the terahertz electromagnetic wave method, it is necessary to make the carrier doping amount of the pn junction in the Si substrate as low as possible. This is because the terahertz electromagnetic wave generated from the IC chip by laser irradiation is absorbed by the Si substrate in the case of a highly doped substrate. Therefore, in order to prevent the terahertz electromagnetic wave from being absorbed by the Si substrate, it is desirable that the carrier dope amount of the IC chip having the inspection pn junction is 5 × 10 ¹⁵ cm ⁻³ or less.

Next, a semiconductor chip inspection method will be described with reference to FIGS.
Here, as shown in FIG. 3, when the semiconductor chip 1 is subjected to excessive pressure applied to the circuit wiring 3 region during mounting and the inspection wiring 5 is deformed (naturally, the circuit wiring 3 is also deformed). )).

  That is, the laser light R is applied from the laser irradiator 11 to the inspection pn junction 6 on the semiconductor chip 1 in which the inspection pn junction 6 is formed on the substrate 2 side and the circuit wiring 3 and its electrode portion 5 are formed. Irradiate.

  When the inspection pn junction 6 is irradiated with the laser beam R, an OBIC current I flows through the inspection wiring 7, and this current generates a magnetic flux (magnetic field) B around it, but the inspection wiring 7 is deformed. Therefore, naturally, the magnetic distribution pattern is disturbed.

  Then, the magnetic flux B is detected by the SQUID element 12, and the detected distribution pattern of the detected magnetic flux B is input to the wiring defect determination unit, where it is determined whether or not it is normal. .

By the way, in the determination by the wiring defect determination unit, the reference distribution pattern of magnetic flux and the detection distribution pattern of magnetic flux are input to the image processing circuit and compared.
The direction of the magnetic flux B is used as the magnetic flux distribution pattern. For example, in FIG. 3, the downward direction is the positive direction (+) and the upward direction is the negative direction (−), and these “+” and “−” Judgment is made using the visualization. That is, when the difference between the two patterns is taken and the directions are different, the part is indicated by another symbol, for example, “Δ”, and when this “Δ” mark is present, the magnetic flux B is It is determined that a disordered wiring failure has occurred.

FIG. 4 shows an example of a magnetic flux distribution pattern in a part of the inspection region of the semiconductor chip, where (a) is a normal reference distribution pattern and (b) is an abnormal detection distribution pattern.
When the difference between the distribution patterns in these two inspection areas is obtained, as shown in FIG. 5, the portion where the abnormality has occurred is indicated by “Δ” and can be easily determined visually. In addition, the magnetic flux distribution pattern is symbolized in this way when the detection capability of the magnetic flux of the SQUID element is as very small as about 0.1 picotesla and when a crack of about 10 μm occurs. This is because there is only a very subtle difference in the magnetic flux distribution, and it is difficult to visually detect the magnetic flux distribution simply by image processing.

  According to the configuration of the semiconductor chip described above, since the inspection pn junction is arranged at a position other than the circuit wiring region, it does not have the inspection pn junction as in the prior art, that is, the pn formed in the circuit wiring region. Unlike what uses bonding, it is possible to perform nondestructive inspection using laser irradiation or the like in any wiring form.

  Further, according to the inspection apparatus and inspection method described above, the OBIC current and the magnetic flux generated by the current are detected by the SQUID element by irradiating the inspection pn junction arranged at a position other than the circuit wiring region with the laser beam. As a result, the non-destructive inspection of the semiconductor chip is performed. Therefore, as compared with the conventional case where the circuit wiring itself is used for inducing the OBIC current, the circuit wiring in the middle of the manufacture of the semiconductor chip is also reduced. Wiring defects can be detected, and even when the circuit wiring itself does not have a pn junction, the inspection using the OBIC current can be performed, and therefore the applicable range of the semiconductor chip to be inspected is greatly increased.

It is a schematic cross section at the time of the test | inspection of the semiconductor chip which concerns on embodiment of this invention. It is a schematic plan view explaining regions other than the circuit wiring region of the semiconductor chip. It is a schematic cross section explaining the inspection method of the same semiconductor chip. The magnetic flux distribution pattern in the semiconductor chip is shown, (a) shows a reference distribution pattern, and (b) shows a detection distribution pattern. It is a magnetic flux distribution figure explaining the judgment method of the wiring defect at the time of the inspection of the semiconductor chip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Silicon substrate 3 Circuit wiring 5 Electrode part 6 Inspection pn junction 7 Inspection wiring 11 Laser irradiator 12 SQUID element

Claims (3)

Forming a test pn junction at a location other than the circuit wiring region of the substrate having a circuit wiring formed on the surface, and forming a test wiring for conducting both electrodes of the test pn junction;
A semiconductor chip characterized in that a part of the inspection wiring is along the circuit wiring. A semiconductor chip inspection apparatus according to claim 1,
A laser irradiator for irradiating a pn junction for inspection with a laser beam;
A SQUID element for detecting a magnetic flux generated when the OBIC current generated in the inspection pn junction flows through the inspection wiring by the irradiation of the laser beam;
And a wiring failure determination unit for comparing the detection distribution pattern of the magnetic flux detected by the SQUID element with the reference distribution pattern of the magnetic flux obtained in the normal case to determine the presence or absence of the wiring failure. Semiconductor chip inspection equipment. A method for inspecting a semiconductor chip according to claim 1,
An OBIC current is generated by irradiating a pn junction for inspection of a semiconductor chip with laser light, and a magnetic flux generated around the OBIC current flowing through the inspection wiring is detected by a SQUID element.
A semiconductor chip characterized by detecting the presence or absence of a wiring defect in a semiconductor chip by comparing a magnetic flux detection distribution pattern detected by the SQUID element with a previously obtained normal magnetic flux reference distribution pattern. Inspection method.

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