JP2544987B2 - Semiconductor element polishing machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor element polishing apparatus for exposing a diffusion layer as a pretreatment for evaluation of the diffusion layer of a semiconductor element such as an LSI.

<Prior Art> The thickness X of the diffusion layer 110 at a specific position of the semiconductor element 100 is reduced.
In order to measure, the polishing that exposes the diffusion layer 110 is required as a pretreatment. Such polishing is performed with a jig 200 as shown in FIG.

The jig 200 includes a substantially cylindrical hollow tubular body 210 having a plurality of window portions 212 formed at a lower end edge portion 211, a columnar body 220 fitted in the tubular body 210, and a lower end surface 221 of the columnar body 220. On screw 240
And a semiconductor element fixture 230 fixed by. The semiconductor element fixture 230 has a taper surface 231 on which the semiconductor element 100 is obliquely attached.

For polishing the semiconductor element 100, as shown in FIG. 5, a cylindrical body 220 having the semiconductor element 100 attached thereto is fitted into a cylindrical body 210, and the cylindrical body 210 is reciprocally slid on the polishing paper 250 together with the cylindrical body 220. By doing. In addition, polishing paper 250
Replace the rough ones to fine ones to finish the polished surface to a mirror surface.

When polishing is completed, chemical treatment (stain etching) is performed, and the diffusion layer 1 of the semiconductor element 100 is processed as follows.
The thickness X of 10 is measured (see FIG. 3).

The thickness X of the diffusion layer 110 is the length Y ′ (= Y) of the diffusion layer 110.
And the angle θ of the tapered surface 231, it can be obtained by X = Y ′ × tan θ.

<Problems to be Solved by the Invention> However, the above-described conventional polishing with a jig has the following problems.

In other words, polishing requires a delicate technique,
It cannot be mechanized or automated. For this reason, although polishing is performed manually, it takes a very long time and moreover, there are many mistakes in the polishing position. Further, there were many variations in polishing due to abrasion of the jig.

Therefore, it is difficult to accurately measure the thickness of the diffusion layer after polishing.

The present invention has been conceived in view of the above circumstances, and an object thereof is to provide a semiconductor element polishing apparatus capable of automatically and accurately polishing a semiconductor element.

<Means for Solving the Problems> A semiconductor element polishing apparatus according to the present invention includes a charged particle optical system for generating a charged particle beam with which a semiconductor element is irradiated,
An XY stage on which the semiconductor element is installed, a secondary electron detector that detects secondary electrons generated by irradiation of a charged particle beam, and a surface of the semiconductor element by a signal from the secondary electron detector. A display unit for displaying, an optical system controller for controlling the charged particle beam, and a stage controller for controlling the XY stage are provided.

<Operation> Polishing work of a semiconductor element by this semiconductor device polishing apparatus can be roughly classified into two works, rough polishing and fine polishing. Further, this work is performed while the operator visually checks the surface of the semiconductor element displayed on the display unit.

The rough polishing is performed to ensure the speed of work, and is performed by a charged particle beam having a large beam diameter. Such polishing is performed by irradiating the charged particle beam at a position slightly apart from the diffusion layer to be exposed and moving (deflecting) the charged particle beam by the optical system controller.

If the operator determines that the polishing has been completed with a thick charged particle beam up to the vicinity of the analyzed region, the charged particle beam is moved so that the portion corresponding to the diffusion layer is irradiated with the beam diameter. Perform precision (finish) polishing with a focused charged particle beam. The polishing exposes the diffusion layer.

<Example> Hereinafter, an example according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a semiconductor device polishing apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing polishing by a charged particle beam, and FIG. 3 is an explanatory diagram of measurement of a diffusion layer thickness. Is.

The semiconductor device polishing apparatus according to the present embodiment includes a semiconductor device 10
The charged particle optical system 10 for generating the charged particle beam B irradiated on 0, the XY stage 20 on which the semiconductor device 100 is installed, and the secondary electron E generated by the irradiation of the charged particle beam B are detected. A secondary electron detection unit 30, a display unit 60 that displays the surface of the semiconductor device 100 by a signal from the secondary electron detection unit 30, an optical system controller 50 that controls the charged particle beam B, and the X- And a stage controller 40 for controlling the Y stage 20.

The charged particle optical system 10 is a charged particle source that generates charged particles.
11 and an accelerator (not shown) that accelerates the generated charged particles. A Ga ion beam is often used as the charged particle beam B. This charged particle beam B
The beam diameter R can be narrowed down to 0.1 μm or less. In order to obtain a good image, it is desirable to narrow the beam diameter R as much as possible.

The XY stage 20 is housed in a sample chamber 15 integrated with the end of the charged particle optical system 10. Such XY
The stage 20 is provided with a tilt stage 21 tilted at a predetermined angle θ (it can be tilted up to 60 °),
The semiconductor element 100 is attached to the tilt stage 21 with silver paste or the like. The sample chamber 15 is evacuated by a cryopump and vacuum pumps 16 and 17.

Secondary electrons E generated by the irradiation of the semiconductor device 100 with the charged particle beam B are detected by the secondary electron detection unit 30 attached to the wall surface of the sample chamber 15. The detection result of the secondary electrons E by the secondary electron detection unit 30 is sent to the control computer 70 via the secondary electron signal amplifier 32.
Sent as 31.

From the control computer 70, the image signal 73 is displayed on the display unit 60.
Is transmitted, and an image of the surface of the semiconductor element 100 is displayed on the display unit 60.

The stage controller 40 moves the XY stage 20 in the XY directions according to the stage control signal 71 sent from the control computer 70. Therefore, the tilt stage 21 provided on the XY stage 20 receives the stage control signal.
You will move according to 71.

Next, the operation of exposing the diffusion layer 110 of the semiconductor element 100 using such a semiconductor element polishing apparatus will be described with reference to FIGS. 2 and 3.

Such operations can be roughly classified into two operations, rough polishing and fine polishing. Further, this operation is performed by the operator when the semiconductor element 10 is displayed on the display unit 60 in an inclined state.
Perform while visually observing the surface of 0.

First, the charged particle beam B is adjusted so that the semiconductor device 100 can be seen most clearly. Then, the semiconductor device 100
Tilt.

 Next, rough polishing will be described.

The rough polishing is carried out in order to ensure the quickness of the work, and is carried out by the charged particle beam B having a beam diameter R = about 2000Å. That is, the thick charged particle beam B has high polishing efficiency, but cannot perform fine polishing. Therefore, such polishing is performed by irradiating the charged particle beam B to a portion slightly apart from the diffusion layer 110 to be exposed and moving the charged particle beam B.

When the operator determines that the polishing with the thick charged particle beam B is completed, the charged particle beam B is moved so that the portion B corresponding to the diffusion layer 110 is irradiated with the beam diameter R. The B part is finely polished by the charged particle beam B focused on <500Å. With the charged particle beam B having a small beam diameter R, fine polishing can be performed though it takes time. By this polishing, the diffusion layer 11
Expose 0.

The semiconductor device 100 includes the tilt stage 2 tilted with θ.
Since it is attached to 1, it is possible to obtain a polishing surface inclined by θ with respect to the diffusion layer 110.

After the polishing with the charged particle beam B of the semiconductor device polishing apparatus, a chemical treatment is applied to remove the portion shown by the broken line in FIG.

The thickness X of the diffusion layer 110 is the length Y ′ (= Y) of the diffusion layer 110.
And the angle θ of the tapered surface 231, it can be obtained by X = Y ′ × tan θ.

<Effects of the Invention> Since the semiconductor element polishing apparatus according to the present invention is configured to expose the diffusion layer by polishing with the charged particle beam while checking the polishing surface, the diffusion layer can be exposed in a short time. The diffusion layer can be exposed uniformly. Therefore, the thickness of the diffusion layer after polishing can be accurately measured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor device polishing apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing polishing by a charged particle beam, and FIG. 3 is an explanatory diagram of measurement of a diffusion layer thickness. , 4th
FIG. 5 is an exploded perspective view of a conventional jig for polishing a semiconductor element, and FIG. 5 is a sectional view illustrating a method of using this jig. 10 ... Charged particle optical system, 20 ... XY stage, 30 ...
Secondary electron detector, 31 ... (from secondary electron detector) signal, 40 ... Stage controller, 50 ... Optical system controller, 60 ... Display unit, B ... Charged particle beam, E ...
Secondary electron, 100 ... Semiconductor element, 110 ... Diffusion layer, B ...
Charged particle beam.

Claims (1)

(57) [Claims] 1. A charged particle optical system for generating a charged particle beam for irradiating a semiconductor element, an XY stage in which the semiconductor element is installed, and secondary electrons generated by the irradiation of the charged particle beam. A secondary electron detector, a display for displaying the surface of the semiconductor element by a signal from the secondary electron detector, an optical system controller for controlling the charged particle beam, and a stage for controlling the XY stage. A semiconductor element polishing apparatus comprising: a controller.