Semiconductor inspection equipment and semiconductor inspection method

Abstract

This invention provides a semiconductor inspection apparatus and semiconductor inspection method that enable accurate measurement of delay. [Solution] The inspection processing unit 100 comprises a photoelectron pulse generating means 101 that generates photoelectron pulses at time intervals for measuring the signal delay occurring in a semiconductor sample to be measured; an irradiation processing means 102 that irradiates the surface of the semiconductor sample with the photoelectron pulses; a short needle / absorption current acquisition means 103 that extracts the short needle / absorption current flowing through the semiconductor sample irradiated with the photoelectron pulses via a short needle 310 that contacts the semiconductor sample; a timing signal output means 104 that outputs a timing signal for the generation of the photoelectron pulses; and a signal delay information creation means 105 that creates signal delay information at the short needle based on the short needle / absorption current extracted by the short needle / absorption current acquisition means 103 and the timing signal output by the timing signal output means 104.

Description

Technical Field

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[0006]

[0001] This invention relates to a semiconductor inspection apparatus and a semiconductor inspection method.

Background Art

[0002] One of the semiconductor failure analysis methods is a failure analysis method called electron beam absorbed current (EBAC) observation shown in Patent Document 1 etc. The method disclosed in this Patent Document 1 utilizes that when an electron beam (primary electron) is incident on a sample, a part of it becomes a weak current (absorbed current) flowing in the sample.

[0003] In EBAC observation, a measurement short needle is applied to a wiring in a sample to make it conductive and an absorbed current is made to flow through the short needle. From the absorbed current locally flowing between the electron beam irradiation position and the measurement short needle, an absorbed current image of the connection wiring is obtained by using the change in the obtained signal amount as contrast. If there is a disconnection point, no contrast appears beyond that point, so the disconnection point can be specified.

[0004] Since this EBAC observation irradiates the electron beam continuously, it has been difficult to perform measurements such as delay. As a solution method, the method shown in Patent Document 2 is known. Patent Document 2 has a method of detecting the time change of the current amount by obtaining the difference between the measurement values before and after the irradiation and freeze of the electron beam during measurement.

[0005] However, since this method has to make the acquisition timings before and after the electron beam irradiation and freeze constant, there is a problem that accurate delay measurement cannot be performed.

[0006] Scanning electron microscopes (SEMs) are known as devices that image the positional information and the amount of secondary electrons detected by scanning the position of an electron beam while irradiating it. Non-patent document 1 introduces ultrafast time-resolved scanning electron microscopes (SUEMs) that combine this with femtosecond lasers, enabling the observation of instantaneous states of materials. While this makes it possible to observe SEM images using instantaneous electron beam irradiation, it has not been applied to EBAC (Electron Biochemical Analysis). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2020-003458 [Patent Document 2] Japanese Patent Publication No. 2010-135684 [Non-patent literature]

[0008] [Non-Patent Document 1] Yusuke Arashida, Samuel Jeong, Kouhei Kawasaki, Yuga Emoto, Godai Noyama, Masaki Hada, Yoshiya Kishibe, Hidemi Shigekawa, Keishi Akada, Shoji Yoshida, and Jun-ichi Fujita, “Visualizing the Transient Response of Local Potentials on Photoconductive Antennas Using Scanning Ultrafast Electron Microscopy”, ACS Photonics 2024, Vol.11, Issue 6, 2171-2175 [Overview of the project] [Problems that the invention aims to solve]

[0009] As described above, conventional semiconductor inspection equipment and semiconductor inspection methods have not been able to accurately measure delay. The present invention has been made in view of the shortcomings of the conventional semiconductor inspection equipment and semiconductor inspection methods described above, and its purpose is to provide a semiconductor inspection equipment and semiconductor inspection method that enables accurate measurement of delay. [Means for solving the problem]

[0010] An embodiment of the present invention is a semiconductor inspection apparatus comprising: a photoelectron pulse generating means for generating photoelectron pulses at time intervals for measuring signal delay occurring in a semiconductor sample to be measured; an irradiation processing means for irradiating the surface of the semiconductor sample with the photoelectron pulses generated by the photoelectron pulse generating means; a short-needle absorption current acquisition means for extracting a short-needle absorption current flowing through the semiconductor sample irradiated with the photoelectron pulses via a short-needle in contact with the sample to be measured; a timing signal output means for outputting a timing signal for the generation of the photoelectron pulses generated by the photoelectron pulse generating means; and a signal delay information creation means for creating signal delay information at the short-needle based on the short-needle absorption current extracted by the short-needle absorption current acquisition means and the timing signal output by the timing signal output means.

[0011] A semiconductor inspection method according to an embodiment of the present invention is characterized by performing an inspection process comprising: a photoelectron pulse generation step of generating photoelectron pulses at time intervals for measuring the signal delay occurring in a semiconductor sample to be measured; an irradiation processing step of irradiating the surface of the semiconductor sample with the photoelectron pulses generated in the photoelectron pulse generation step; a short-needle absorption current acquisition step of extracting the short-needle absorption current flowing through the semiconductor sample irradiated with the photoelectron pulses via a short-needle in contact with the sample to be measured; a timing signal output step of outputting a timing signal of the generation of the photoelectron pulses generated in the photoelectron pulse generation step; and a signal delay information creation step of creating signal delay information at the short-needle based on the short-needle absorption current extracted in the short-needle absorption current acquisition step and the timing signal output in the timing signal output step. [Brief explanation of the drawing]

[0012] [Figure 1] Block diagram of a semiconductor inspection apparatus according to an embodiment of the present invention. [Figure 2] This figure shows the timing signal (reference pulse) (Figure 2(a)), short-hand absorption current pulse (Figure 2(b)), stage absorption current pulse (Figure 2(c)), and short-hand stage delay amount (Figure 2(d)) obtained by the inspection processing unit of the semiconductor inspection apparatus according to an embodiment of the present invention. [Figure 3] A flowchart illustrating the procedure for a semiconductor inspection method implemented by a semiconductor inspection apparatus according to an embodiment of the present invention. [Figure 4] A diagram showing another configuration of the photoelectron pulse generating means employed in the semiconductor inspection apparatus according to an embodiment of the present invention. [Modes for carrying out the invention]

[0013] The semiconductor inspection apparatus and semiconductor inspection method according to the present invention will be described below with reference to the drawings. In each figure, the same components are denoted by the same reference numerals, and redundant explanations are omitted. Figure 1 shows a block diagram of the semiconductor inspection apparatus according to the present invention. The semiconductor inspection apparatus according to the embodiment comprises a photoelectron pulse generating means 101, an irradiation work processing means 102, a short needle / absorption current acquisition means 103, a timing signal output means 104, and an inspection processing unit 100.

[0014] The photoelectron pulse generating means 101 generates photoelectron pulses at time intervals for measuring the signal delay occurring in a semiconductor sample to be measured. In this embodiment, the photoelectron pulse generating means 101 comprises a pulse laser generator 201 which functions as a pulse laser generating unit that generates a pulsed laser, a wavelength conversion unit 202 which converts the wavelength of the generated pulse laser to increase its energy (for example, by converting it to ultraviolet light), and an electron gun 203 which functions as an electron source that generates photoelectron pulses by receiving the wavelength-converted pulse and performing a photoelectric effect. In this embodiment, for example, the electron gun 203, which is the electron source, generates photoelectron pulses by the photoelectric effect when irradiated with ultraviolet light.

[0015] Specifically, the pulsed laser generated by the pulsed laser generator 201 is converted to ultraviolet light by the wavelength conversion unit 202 and output as an ultraviolet pulse from the wavelength conversion unit 202. The ultraviolet pulse's direction of travel is changed toward the electron gun 203 by, for example, a perforated mirror 204 and sent to the electron gun 203. The electron gun 203 has a mechanism for photoelectric conversion, and when an ultraviolet pulse arrives, it receives irradiation and generates and outputs a photoelectron pulse through the photoelectric effect.

[0016] The photoelectron pulse output from the electron gun 203 travels through the perforated mirror 204 and towards the semiconductor sample 800 placed on the stage 300. Along the irradiation path of the photoelectron pulse from the electron gun 203 to the semiconductor sample 800, a focusing lens 211, a scanning lens 212, and an objective lens 213 are provided, which together with the electron gun 203 constitute the irradiation operation processing means 102. The irradiation operation processing means 102 irradiates the surface of the semiconductor sample 800 with the photoelectron pulse generated by the electron gun 203.

[0017] The short needle - absorption current acquisition means 103 provided in the semiconductor inspection apparatus according to the present embodiment extracts the short needle - absorption current flowing through the semiconductor sample 800 irradiated with the photoelectron pulse via the short needle 310 that contacts the semiconductor sample 800. That is, when a photoelectron pulse is incident on the semiconductor sample 800, a part of it becomes an absorption current, which is a weak current flowing through the semiconductor sample 800. The present embodiment adopts a configuration in which a measurement short needle 310 is applied to and electrically connected to the wiring in the semiconductor sample 800, and the absorption current is extracted from the short needle 310.

[0018] The timing signal output means 104 of the present embodiment outputs a timing signal for the generation of the photoelectron pulse generated by the photoelectron pulse generation means 101. This timing signal output means 104 includes a beam splitter 320, which is a branching section that branches the pulsed laser generated by the pulsed laser generation device 201 having the function as the above - mentioned pulse laser generation section. Further, the timing signal output means 104 includes an optical delay section 330 that delays the pulsed laser branched by the beam splitter 320, which is the above - mentioned branching section, to obtain the timing signal for the generation of the photoelectron pulse, and photoelectrically converts this output to obtain a timing signal (reference pulse) and outputs it to the inspection processing section 100. The optical pulse, which is the timing signal for the generation of the photoelectron pulse, is given to the inspection processing section 100.

[0019] The inspection processing unit 100 provided in the semiconductor inspection apparatus according to this embodiment is provided with signal delay information creation means 105. This signal delay information creation means 105 creates signal delay information in the short needle 310 based on the short needle / absorption current taken out by the above-mentioned short needle / absorption current acquisition means 103 and the timing signal output by the above-mentioned timing signal output means 104.

[0020] By this inspection processing unit 100, an absorption current image of the connection wiring can also be obtained by using the change in the obtained signal amount as contrast from the absorption current that locally flows between the irradiation position when the photoelectron pulse is irradiated on the surface of the semiconductor sample 800 and the measurement short needle 310.

[0021] The semiconductor inspection apparatus according to this embodiment includes stage / absorption current acquisition means 106. The stage / absorption current acquisition means 106 is arranged on the bottom surface side of the semiconductor sample 800 and extracts stage / absorption current from a stage 300 configured to be able to take in absorption current from the substrate of the semiconductor sample 800. The above-mentioned signal delay information creation means 105 creates signal delay information in the stage 300 based on the stage / absorption current taken out by the above-mentioned stage / absorption current acquisition means 106 and the timing signal output by the above-mentioned timing signal output means 104.

[0022] With the above configuration, by the inspection processing unit 100, as shown in FIG. 2, a light pulse (FIG. 2(a)), which is a timing signal for the generation of the photoelectron pulse, a short needle absorption current pulse (FIG. 2(b)), a stage absorption current pulse (FIG. 2(c)), and a short needle-stage delay amount (FIG. 2(d)) can be obtained.

[0023] Further, the inspection processing unit 100 includes two-dimensional mapping information creation means 110 that performs scanning irradiation to sequentially change the position of the surface of the semiconductor sample 800 on which the photoelectron pulse is irradiated by the irradiation operation processing means 102 to obtain the absorption current amount and / or signal delay information, and creates two-dimensional mapping information corresponding to the position of the surface of the semiconductor sample 800.

[0024] The above configuration allows for synchronized waveform observation. As shown here, photoelectron pulses are generated from a pulsed laser and irradiated onto the sample. A portion of the electron beam irradiated onto the sample is absorbed by the sample and becomes an absorption current. The absorption current is detected by the short needle 310 after passing through the LCR characteristics of the sample from the irradiated location. Some of the absorption current flows through the short needle 310, and some flows through the stage 300, and it is possible to measure both or either of them. Meanwhile, the pulsed laser is introduced to the inspection processing unit 100 by a beam splitter. Since they originate from the same pulsed laser, the delay can be measured by comparing the timing of the photopulse and the absorption current pulse. By using a function similar to that of an SEM, the electron beam is scanned, and the LCR characteristics for each position are detected, making it possible to perform two-dimensional mapping of characteristics such as delay time and signal amount.

[0025] Figure 3 shows a flowchart illustrating the procedure of a semiconductor inspection method implemented by a semiconductor inspection apparatus according to an embodiment of the present invention. Specifically, in step S11, photoelectron pulses with time intervals for measuring signal delay are generated. Next, in step S12, the generated photoelectron pulses are irradiated onto the surface of the semiconductor sample. Next, in step S13, the short-point absorption current flowing through the semiconductor sample irradiated with the photoelectron pulses is extracted.

[0026] Next, in step S14, the stage absorption current is extracted from a stage configured to acquire absorption current from the semiconductor sample substrate. Then, in step S15, the timing signal for the generation of the photoelectron pulses is output.

[0027] Next, in step S16, signal delay information for the short hand is created based on the short hand absorption current and the timing signal. Next, in step S17, signal delay information for the stage is created based on the stage absorption current and the timing signal.

[0028] Next, in step S18, scanning irradiation is performed to sequentially change the surface position of the semiconductor sample to obtain absorbed current amount and / or signal delay information, and two-dimensional mapping information corresponding to the surface position of the semiconductor sample is created.

[0029] Figure 4 shows another configuration of the photoelectron pulse generation means 101. In this example, instead of going through the process of generating a pulsed laser device 201 → "wavelength conversion unit 202 that converts the wavelength to increase the energy of the generated pulsed laser (for example, converting the wavelength to ultraviolet light)" → "electron gun 203 that functions as an electron source that generates photoelectron pulses by receiving the wavelength-converted pulse and performing a photoelectric effect to convert it into a photoelectron pulse", an electron beam generation unit 401 that directly generates an electron beam is used. The photoelectron pulse generating means 101 is created by an electron beam generating unit 401 that generates an electron beam and a photoelectron pulse generating unit 402 that controls the passage or non-passage of the electron beam to produce photoelectron pulses at time intervals for measuring the signal delay occurring in the semiconductor sample. The time interval generated by the photoelectron pulse generating unit 402 is provided to the inspection processing unit 100 as a timing signal to perform its operation. This configuration can also be expected to produce the same effects as in the case of Figure 1. [Explanation of Symbols]

[0030] 100 Inspection Processing Unit 101 Photoelectron pulse generating means 102 Irradiation processing means 103 Short needle / absorption current acquisition method 104 Timing signal output means 105 Signal delay information creation means 106 Stage Absorption Current Acquisition Method 110 Two-dimensional mapping information creation means 201 Pulse laser generator 202 Wavelength conversion section 203 Electron Gun 204 Perforated Mirror 211 Focusing lens 212 Scanning Lens 213 Objective lens 300 stages 310 Hour hand 320 Beam Splitter 330 Optical delay section 401 Electron beam generation unit 402 Photoelectron pulse generation unit 800 Semiconductor Samples

Claims

1. A photoelectron pulse generator that generates photoelectron pulses at time intervals for measuring the signal delay occurring within a semiconductor sample to be measured, An irradiation processing means for irradiating the surface of the semiconductor sample with photoelectron pulses generated by the photoelectron pulse generating means, A short needle / absorption current acquisition means for extracting the short needle / absorption current flowing through the semiconductor sample irradiated with a photoelectron pulse via a short needle that contacts the semiconductor sample, A timing signal output means that outputs a timing signal for the generation of photoelectron pulses generated by a photoelectron pulse generating means, An inspection processing unit comprising a signal delay information creation means for creating signal delay information for the short needle based on the short needle absorption current extracted by the short needle absorption current acquisition means and the timing signal output by the timing signal output means, A semiconductor inspection apparatus characterized by comprising the following:

2. The system comprises a stage positioned on the bottom side of the semiconductor sample and configured to capture absorption current from the substrate of the semiconductor sample, and a stage / absorption current acquisition means for extracting stage / absorption current from the stage, The semiconductor inspection apparatus according to claim 1, characterized in that the signal delay information creation means creates signal delay information in the stage based on the stage absorption current extracted by the stage absorption current acquisition means and the timing signal output by the timing signal output means.

3. The semiconductor inspection apparatus according to claim 1 or 2, characterized in that the inspection processing unit comprises two-dimensional mapping information creation means, which obtains absorption current amount and / or signal delay information by performing scanning irradiation to sequentially change the position of the surface of the semiconductor sample irradiated with photoelectron pulses by the irradiation work processing means, and creates two-dimensional mapping information corresponding to the position of the surface of the semiconductor sample.

4. The photoelectron pulse generating means is A pulsed laser generator that generates pulsed lasers, A wavelength conversion unit that converts the wavelength in order to increase the energy of the generated pulsed laser, An electron source that generates photoelectron pulses is provided, which includes a photoelectric conversion unit that receives a wavelength-converted pulse and converts it photoelectrically to produce a photoelectron pulse. The semiconductor inspection apparatus according to claim 1, characterized by comprising the following:

5. The timing signal output means is, A branching unit that branches the pulsed laser generated by the pulsed laser generation unit, A light delay unit that delays the pulsed laser branched by the branching unit to obtain a timing signal for the generation of the photoelectron pulses. The semiconductor inspection apparatus according to claim 4, characterized by comprising the following features.

6. The photoelectron pulse generating means is An electron beam generating unit that generates an electron beam, A photoelectron pulse generation unit that controls the passage and non-pass of the electron beam to generate photoelectron pulses at time intervals for measuring the signal delay occurring within the semiconductor sample. The semiconductor inspection apparatus according to claim 1, characterized by comprising the following:

7. A photoelectron pulse generation step that generates photoelectron pulses at time intervals for measuring the signal delay occurring in the semiconductor sample to be measured, An irradiation process step in which the photoelectron pulse generated in the photoelectron pulse generation step is irradiated onto the surface of the semiconductor sample, A short needle absorption current acquisition step involves extracting the short needle absorption current flowing through the semiconductor sample irradiated with a photoelectron pulse via a short needle that is in contact with the semiconductor sample, A timing signal output step that outputs a timing signal for the generation of photoelectron pulses generated in the photoelectron pulse generation step, A semiconductor inspection method characterized by performing an inspection process by creating a signal delay information creation step that creates signal delay information for the short needle based on the short needle and absorption current extracted in the short needle and absorption current acquisition step and the timing signal output in the timing signal output step.

8. The system includes a stage absorption current acquisition step for extracting a stage absorption current from a stage positioned on the bottom side of the semiconductor sample and configured to acquire absorption current from the substrate of the semiconductor sample, The semiconductor inspection method according to claim 7, characterized in that the signal delay information creation step creates signal delay information at the stage based on the stage absorption current extracted in the stage absorption current acquisition step and the timing signal output in the timing signal output step.

9. The semiconductor inspection method according to claim 7 or 8, characterized in that the inspection process includes a step of creating two-dimensional mapping information, in which scanning irradiation is performed to sequentially change the position of the surface of the semiconductor sample irradiated with photoelectron pulses in the irradiation work process step to obtain absorbed current amount and / or signal delay information, and two-dimensional mapping information corresponding to the position of the surface of the semiconductor sample.

10. In the photoelectron pulse generation step, A pulsed laser generator that generates pulsed lasers, A wavelength conversion unit that converts the wavelength in order to increase the energy of the generated pulsed laser, An electron source that generates photoelectron pulses is provided, comprising a photoelectric conversion unit that receives a wavelength-converted pulse and uses the photoelectric effect to convert it into a photoelectron pulse, and The semiconductor inspection method according to claim 7, characterized in that it generates photoelectron pulses using [a specific method].

11. In the timing signal output step, A branching unit that branches the pulsed laser generated by the pulsed laser generation unit, A light delay unit that delays the pulsed laser branched by the branching unit to obtain a timing signal for the generation of the photoelectron pulses. The semiconductor inspection method according to claim 10, characterized in that it outputs a timing signal using

12. In the photoelectron pulse generation step, An electron beam generating unit that generates an electron beam, A photoelectron pulse generation unit that controls the passage and non-pass of the electron beam to generate photoelectron pulses at time intervals for measuring the signal delay occurring within the semiconductor sample. The semiconductor inspection method according to claim 7, characterized in that it generates photoelectron pulses using [a specific method].

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