JP2667275B2 - Method of manufacturing sample for analysis of semiconductor device and device for marking sample for analysis - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sample for analysis of a semiconductor device and a device for marking the sample.

2. Description of the Related Art Conventionally, when analyzing a specific location, a semiconductor device is analyzed using a sample in which a location is visually observed with an optical microscope and a mark is attached with a needle or ink. This method cannot be used for the analysis of all semiconductor devices at present, as the method of manufacturing semiconductor devices has become finer. In particular, it cannot be used for analyzing one element of a highly integrated semiconductor device such as a memory.

On the other hand, conventionally, a device for attaching a symbol to a semiconductor substrate or the like is:
A type in which a laser pulse is applied to a small portion of the surface, and the energy of the laser pulse is applied so that the semiconductor material is melted only at the center of the small portion of the surface on the surface corresponding to the desired surface pattern and partially evaporated. (Japanese Patent Laid-Open Publication No. 1-41245). This method cannot be used for analysis because a partially evaporated gas is adsorbed on the surface, re-adhered to the surface of the semiconductor device, or caused a serious damage to the semiconductor substrate with crystal defects.

A device called a laser trimmer is a device that melts and cuts a fuse of a circuit in a semiconductor device in a wafer state as shown in FIG. 3, but has a fixed drive unit of the semiconductor device as a sample to be analyzed. This type detects a central portion of the wafer and cuts fuses of a predetermined size and arranged at a predetermined position. However, when analyzing a semiconductor device, since there are various kinds of semiconductor devices and manufacturing rules, symbols can be attached in a chip state, and it is necessary to easily change the size and quality of the symbols. It is becoming.

SUMMARY OF THE INVENTION In the conventional method of manufacturing a sample for analysis, when analyzing a semiconductor device, it is difficult to add a symbol to a specific semiconductor element of a miniaturized semiconductor device chip. There is a problem that it cannot be applied to a material, and furthermore, it cannot be used for analysis of a semiconductor substrate because crystal defects occur due to damage. In addition, since the semiconductor material is partially melted and evaporated, there is a problem that the evaporated substance is reattached and cannot be applied to surface analysis. In addition, it is not possible to automatically apply any quality symbol of any size anywhere on the chip.

Means for Solving the Problems The present invention is to provide a converged laser beam generated from a laser source, by attaching a plurality of different symbols near a portion to be analyzed on a semiconductor device, and then using the symbol as a reference for the semiconductor device. This is a method for manufacturing a sample for analysis of a semiconductor device, which is capable of performing the analysis. Further, in order to easily perform the above manufacturing method, the present invention provides a driving system on a fixed base of a semiconductor substrate placed in a chamber capable of irradiating a semiconductor substrate with a laser beam and controlling an atmosphere, A control unit, further provided with a control unit for the lens system and the laser system, further comprising a reflector in the middle of the laser beam, and a detector for detecting the laser beam reflected by the reflector, The control signal is taken into the control unit to detect the position, and each control unit is collectively controlled by one control unit, and is automatically placed in an unspecified place of the semiconductor device in any size and any quality. It is a signing device that can sign.

In this way, the laser of the semiconductor device is irradiated to produce a sample having a plurality of different symbols in the vicinity of the defective element on the semiconductor device. Can be easily identified and analyzed to identify the cause of the failure.
Further, in order to easily attach a symbol to the sample for analysis of the semiconductor device, a device provided with a drive system in the semiconductor device fixing portion is placed in a chamber capable of controlling an atmosphere during laser light irradiation, and the drive system is provided with a drive system. A control unit, a control unit for a lens system and a laser system, and a reflector for detecting the laser beam reflected by the reflector in the middle of the laser beam; The control signal is taken into the control unit, the position is detected, and each control unit is collectively controlled by one control unit. By using a device that can give a quality symbol, a sample for analyzing a defective element can be easily and accurately manufactured.

Embodiment An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a system diagram of a semiconductor device analyzing apparatus according to the present invention. 1
Megabit DRAM wiring patterns, for example, hydrofluoric acid:
After removing the sample by putting it in a liquid of water = 1: 1, the failure analysis of one bit having a failure in the electrical characteristics was performed using a transmission electron microscope. YAG as laser source 1 for marking
A laser was used. Using a glass lens of the converging lens 2 in the adjacent block where the defective bit exists, the laser beam 3
Is irradiated with a beam diameter of, for example, 0.2 mm and a laser energy of, for example, 0.8 μJ in an oxygen atmosphere. Formed. This recrystallization region 4
Is performed in an oxygen atmosphere and becomes an oxide film, which can be recognized by an optical microscope, and the vicinity of a defective portion can be easily searched. Further, the YAG laser of the laser source 1 is used for the bits before and after the defective bit and the laser energy is set to, for example, 0.8 μJ by the glass lens of the converging lens 2 so that the beam diameter of the laser light is converged to a diameter of 1 μm. Irradiate the 1 Mbit DRAM with the wiring pattern removed,
Recrystallization is performed in an inert gas atmosphere such as a nitrogen atmosphere. Since the recrystallization region 4 having a diameter of 1 μm is performed in a nitrogen atmosphere, solid-phase epitaxial growth occurs. These two
The type symbol determines the distance from the defective element in consideration of the re-solid solution atmosphere and the like so that damage, crystal defects, and stress when the recrystallized region 4 is formed do not affect the element to be analyzed. . Next, based on the oxidized portion having a diameter of 0.2 mm, a disk having a diameter of 3 mm is cut out using an ultrasonic disk cutter. Further, the surface was polished from the back surface, mirror-finished to a thickness of 40 μm, and then etched using an ion etching apparatus until the opening was obtained. This sample was fixed on a sample holder of a transmission electron microscope and observed. In this observation, there are recrystallized regions 4 having a diameter of 1 μm which are formed by solid phase epitaxial growth before, after, right and left of the defective bit. The recrystallized region 4 could be used as a reference when observing a transmission image because stacking faults were generated by solid phase growth in the horizontal direction and solid phase growth in the vertical direction. As a result of this analysis, it was possible to observe a defective bit whose electrical characteristics were measured, and this defect did not serve as a capacitor because charge was leaked at the element isolation edge due to the occurrence of stacking faults including copper. I understand. From the above examples, it was found that the effect of this analysis was great. By changing the laser beam diameter, the present invention can be applied not only to a 1-Mbit DRAM but also to a semiconductor device having an integration degree of 4 Mbit DRAM or more.

An embodiment of a signing device will be described to facilitate the above analysis. FIG. 2 is a system diagram of the analyzer of the present invention. A YAG laser was used as the laser source 1. In order to perform the process from reference detection to recrystallization with one YAG laser,
It can be freely changed from 0.1 μJ to 3 μJ. In the case of recrystallization, it depends on the semiconductor material,
The energy changes depending on the material. The method of detecting the reference is performed, for example, at a laser energy of 0.1 μJ, the laser light reflected by the reflector 13 is detected by the detector 14 to recognize the reference cross pattern, and the origin on the chip is determined. I do. In order to perform the above two controls, a laser power / position control unit 8 is used.

The focusing lens 2 and the slit 6 are used so that the laser beam diameter can be freely set in accordance with the manufacturing rule of the semiconductor device 5 and the size of the symbol. Focusing lens 2 and slit 6
Is controlled by changing the position of the lens and the size of the slit by the focusing lens system control unit 9. Semiconductor device 5
Are fixed to the semiconductor device fixed drive unit 7. The drive system uses a step motor having an accuracy of ± 0.15 μm in each of the X, Y, and Z axis directions, and is controlled by the drive control unit 10.
The semiconductor device fixed drive section 7 is evacuated to vacuum, and is contained in a chamber 12 so that solid solution recrystallization can be performed by changing an atmosphere such as an oxygen atmosphere, a nitrogen atmosphere, or an arsenic atmosphere. Further, a laser power, a position control unit 8, a focusing lens system control unit 9, and a drive control unit 10 are controlled by a data input unit 11, and input a semiconductor material, a position to attach a symbol, a size of the symbol, etc. It functions as a terminal that controls the beam diameter of the laser beam, the drive system, and the like. By using this system, failure analysis using a 1-Mbit DRAM transmission electron microscope was possible, and the analysis time was almost 20 hours, which is almost the same as the sample preparation time of the transmission electron microscope. By changing the laser source 1, it can be used for analysis other than the semiconductor device.

According to the present invention, by oxidizing or recrystallizing a semiconductor material using a laser, it is possible to perform analysis after fabricating a sample with a symbol, and to analyze an element that is actually defective. became. In addition, by using the analysis apparatus of the present invention, analysis can be performed in an analysis time of about 20 hours, which is almost the same as the sample preparation time of the transmission electron microscope.

[Brief description of the drawings]

FIG. 1 is a system diagram for explaining a method of analyzing a semiconductor device of the present invention, FIG. 2 is a system diagram of an analyzing device of the present invention, and FIG. 3 is a system diagram for explaining a conventional example. 1 laser source, 2 focusing lens, 3 laser light,
4 Recrystallization region 5 Semiconductor device 6 Slit 7 Semiconductor device fixed drive unit 8 Laser power / position control unit 9 Focusing lens system control unit 10 Drive controller, 11 Data input unit, 12 Chamber, 13
... Reflector, 14 ... Detector, 21 ... Laser source, 22 ... Converging lens, 23 ... Slit, 24 ... Laser light, 25 ... Semiconductor device, 26 ... Semiconductor device fixed drive unit, 27 ... Drive unit control unit, 28 data input unit.

Claims (2)

(57) [Claims] When a symbol for specifying an analysis position on a semiconductor substrate is provided, a first energy having an energy that does not evaporate the semiconductor substrate material in an oxidizing atmosphere is provided near a predetermined position to be analyzed. Irradiating a focused laser beam to form an oxide film region; and a plurality of regions near the predetermined position where the analysis is to be performed and different from the oxide film region. Irradiating a second focused laser beam having a smaller beam diameter than the focused laser beam to provide a region substantially free of an oxide film and recrystallizing the semiconductor substrate;
Method for manufacturing sample for analysis of semiconductor device. 2. A laser source, a lens for converging laser light emitted from the laser source, a converging lens system control unit for controlling the lens, a slit for determining an irradiation area of the laser light, and a semiconductor substrate for the laser light. Determine the irradiation position, a control unit for controlling the irradiation energy of the laser light, and a drive table for installing a semiconductor substrate that is marked to identify the analysis position where the laser light is irradiated, the drive table, The analysis is characterized in that the semiconductor substrate provided is provided in a chamber capable of irradiating the laser beam and changing the internal atmosphere to at least an oxidizing atmosphere or an inert gas atmosphere. Sample signing device.