JPH0342618Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Use The present invention relates to an apparatus for correcting defects in semiconductor manufacturing masks such as photomasks and reticles used in semiconductor manufacturing processes.

The purpose of the defect correction location detection device described above is to irradiate an ion beam onto the mask and detect the emitted secondary ions in order to identify the mask pattern location and the exposed mask substrate location. Secondary ion mass spectrometer used in ion beam mask repair equipment.

b. Prior Art There are two general methods for observing mask repair locations using secondary ions emitted by ion beam irradiation.

One is a method using a quadrupole mass spectrometer,
Another method is to use a sector-type mass spectrometer. The latter is a conventional example of the present invention, and has a configuration as shown in FIG. Sample 2
2 is irradiated with an ion beam 21, and the secondary ions 23 emitted thereby are focused at the position of the slit 25 by a drawing lens 24.
Furthermore, only secondary ions 27 having a desired mass are passed through a slit 28 by a sector magnet 26, and detected by an ion detector 29. At this time, the sector magnet 26 can be operated by appropriately selecting the incident angle ε1 and the output angle ε2.
The secondary ions 27 can be focused at the same position (the position of the slit 28) at the same time in the plane of the paper and in a plane perpendicular to the plane of the paper, thereby increasing the detection efficiency of the secondary ions 27.

c Problems to be Solved by the Invention In order to detect a plurality of different secondary ions using the conventional device described above, sector magnet 2 is required.
By changing the magnetic field 6, secondary ions of a desired mass were allowed to pass through the slit 28 and detected. However, with this method, for the purpose of detecting a plurality of secondary ions, simultaneous detection is not possible and the detection efficiency is not good. Furthermore, if the detection efficiency is not good, the ion beam irradiation time becomes long and the damage to the sample due to the ion beam irradiation increases, which is not preferable. In a mask repair apparatus, a method of observing a repaired area using secondary ions requires detection of two different ions. In order to increase the throughput and to minimize damage to the sample 22 due to ion beam irradiation, it is sufficient to simultaneously detect other secondary ions 30 in addition to the secondary ions 27. However, secondary ions 27
is the method of appropriately selecting the incident angle ε1 and the exit angle ε2 described above, and the slit 28 is placed at an appropriate position.
It is possible to simultaneously focus on the position of , within the plane of the paper and within a plane perpendicular to the plane of the paper, increasing detection efficiency. However, at this time, the secondary ions 30 cannot be focused on the same position at the same time in the plane of the paper and in a plane perpendicular to the plane of the paper, and the detection efficiency of the secondary ions 30 is not good. In general, by appropriately selecting the incident and exit angles, multiple ions with different masses are simultaneously focused at the same position in two orthogonal planes including the direction of travel of each ion (hereinafter, spatial doubling). (called imaging)
I can't do it. Furthermore, when detecting multiple ions with different masses simultaneously, a slit and ion detector unit is installed on the trajectory of each mass-separated secondary ion to be detected, and the trajectory of these secondary ions is is obtained by calculation. However, these orbits do not allow accurate knowledge of the edge magnetic field. Therefore, even if the above unit is installed on the calculated orbit, the actual trajectory will be slightly different from the calculated one. Furthermore, due to assembly errors of the unit, a deviation occurs between the actual trajectory and the position of the unit, resulting in a decrease in detection efficiency.

The present invention is intended to solve the above-mentioned problems in a secondary ion mass spectrometer used in an ion beam mask repair apparatus that observes secondary ions emitted from a semiconductor manufacturing mask by ion beam irradiation.

d Means for solving the problem Spatial double imaging is performed independently of the slit and ion detector unit placed on the mass-separated secondary ion trajectory that satisfies the conditions for spatial double imaging. A unit consisting of a slit and an ion detector is installed on another mass-separated secondary ion beam orbit that deviates from the conditions of A static electrode having a pair of opposing electrodes having the same plane of symmetry as opposing magnetic poles (not shown) constituting the net, and another pair of opposing electrodes having a plane of symmetry perpendicular to this plane of symmetry. This is a means of arranging an electric quadrupole lens. Function: Secondary ions emitted by ion beam irradiation onto a mask for semiconductor manufacturing are drawn into a sector magnet by a lens, and the secondary ions are subjected to mass separation. One of the desired two different secondary ions passes on a mass-separated secondary ion trajectory that satisfies the above-mentioned spatial double imaging condition, and spatially passes onto a slit placed on the trajectory. A double image is formed and enters the ion detector, where it is detected with high detection efficiency. Another desired secondary ion passes through another mass-separated secondary ion beam trajectory that deviates from the spatial double imaging condition, and passes through the stationary ion beam placed on the trajectory. The light enters the electric quadrupole lens. The electrostatic quadrupole lens can be given a deflection function or a focusing function by changing the voltage applied to each electrode. Moreover, these functions can be operated simultaneously. Therefore, by applying an appropriate voltage to each electrode of the electrostatic quadrupole lens, the secondary ions incident on the electrostatic quadrupole lens are substantially directed to the north of the slit placed behind it. A spatially double image is formed at the center of the slit and enters the ion detector, where it is detected with high detection efficiency.

f Example The example shown in Figure 1 assumes that the sample is a photomask in which a chrome mask pattern is formed on a glass substrate, and secondary silicon ions emitted from the sample are detected. By detecting secondary chromium ions, the mask pattern can be identified.

Embodiments of the present invention will be described below with reference to the drawings. In Figure 1, 1 is an ion beam,
The semiconductor manufacturing mask 2 is irradiated, and secondary ions 3 are emitted. 4 is a retraction lens, and this 2
Next, the ions 3 are drawn in and focused at the position of the slit 5. 6 is a sector magnet, 7 is a silicon secondary ion, the rotation angle within the sector magnet is selected to be 120 degrees, and the incident angle ε1 is
40 degrees, the emission angle ε2 is 40 degrees, the distance l1 between the slit 5, which is the light source position of the sector magnet, and the sector magnet is 80 mm, and the image of the sector magnet for silicon secondary ions (first secondary ions). By selecting the distance 12 between the position of the first slit 9 and the exit opening of the first secondary ion (silicon ion) of the sector magnet to be 40.5 mm, spatial double bonding is achieved for secondary ions of silicon. The image condition is met. 8 is a secondary ion of chromium (second 2
The radius of rotation of the secondary ions of chromium within the sector magnet is 1.36 times that of silicon, so the radius of rotation for chromium is 92.2 degrees. 10 is a first ion detector for detecting secondary ions 7 of silicon.

11 is an electrostatic quadrupole lens disposed on the orbit of secondary chromium ions, that is, at the exit port of the second secondary ions (chromium ions);
are a second slit for secondary chromium ions and a second ion detector located behind the electrostatic quadrupole lens 11, respectively.

The above is an example for observing a mask patterned with chrome, but there are also other examples.
Secondary ions of silicon and gold can also be detected using a mask or the like in which gold turns are formed on a silicon substrate by changing the position of the unit consisting of a slit and an ion detector.

g Effects of the Invention As explained above, by combining the two-channel sector magnet and the electrostatic quadrupole lens according to the present invention, two secondary ions with different masses can be spatially double-imaged at the same time. The detection efficiency can be greatly improved by the deflection effect, and the axis misalignment between the trajectory of the secondary ions and the unit consisting of the slit and the channeltron (or electron multiplier tube) can be corrected, which increases the detection efficiency. can be further improved. This improved detection efficiency also reduces beam irradiation time and minimizes damage to the sample.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the secondary ion mass spectrometer of the present invention. FIG. 2 shows a conventional example. 1... Ion beam, 2... Sample, 3... Secondary ion, 4... Entrainment lens, 5... Slit, 6... Sector magnet, 7... Secondary ion (silicon),
8... Secondary ion (chromium), 9... First slit,
DESCRIPTION OF SYMBOLS 10... First ion detector, 11... Electrostatic quadrupole lens, 12... Second slit, 13... Second ion detector, 21... Ion beam, 22... Mask for semiconductor manufacturing (material), 23... Secondary ion , 24... Retraction lens, 25... Slit, 26... Sector magnet, 27, 30... Secondary ion, 28... Slit, 29... Ion detector.

Claims (1)

[Scope of claim for utility model registration] A drawing lens that draws in secondary ions generated by irradiating a sample with an ion beam;
A secondary ion of an ion beam device comprising a sector magnet that separates the secondary ions drawn in by the drawing lens into secondary ions of different masses, and a detector that detects the secondary ions separated by the sector magnet. In the mass spectrometer, a first ion detector is provided at a first secondary ion exit port of the sector magnet, and a first ion detector is provided at a second secondary ion exit port of the sector magnet via an electrostatic quadrupole lens. A secondary ion mass spectrometer of an ion beam device, characterized by comprising two ion detectors.