JP2000055875A - Light scan type apparatus for measuring second dimensional concentration distribution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive light scan type apparatus in a compact constitution for measuring a two-dimensional concentration distribution which can scan a light as desired without moving a sample. SOLUTION: In the light scan type apparatus for measuring a two-dimensional concentration distribution which is constituted with a sensor face 7 at one of a semiconductor substrate so that the semiconductor substrate is irradiated with a light 13 from a light source 14 in two dimensions from the side of the other face semiconductor substrate, two linear stages 20, 29 which move in directions not parallel to each other are set at the side of the other face of the semiconductor substrate, and reflecting members 25, 24 for changing a course of the light 13 from the light source 14 are set on the linear stages 20, 29. When the linear stages 20, 29 are moved, the semiconductor the light 13 substrate is irradiated with in two dimensions from the side of the other face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate having a sensor surface on one surface, and two-dimensionally irradiating the semiconductor substrate with light from a light source from the other surface side. Optical scanning type two-dimensional concentration distribution measuring apparatus.

[0002]

BACKGROUND OF THE INVENTION As the optical scanning type two-dimensional density distribution measuring device, for example, Jpn. J. Appl. Phys. Vo
l. 33 (1994) pp L394-L397, as described in LAPS (Light-Addresses).
sable Potentiometric Sens
or), which measures the potential generated on the surface of the pH-sensitive film by employing the method. In such a device, E
The measurement can be performed by scanning the IS (Electrolyte E-Insulator I-Semiconductor S) structure with light and extracting the AC photocurrent induced in the semiconductor by this optical scanning.

[0003] The applicant of the present invention has disclosed such a technique relating to an optical scanning type two-dimensional density distribution measuring apparatus, for example, in Japanese Patent Application No. 8-93064 (Japanese Patent Application Laid-Open No. 8-320301) and Japanese Patent Application No. 8-289373. No. (JP-A-10-113199)
Japanese Patent Application No. 9-49694 (JP-A-9-29236).
No. 5) and many others have applied for patents.

[0004]

2. Description of the Related Art In the optical scanning type two-dimensional density distribution measuring apparatus, when optical scanning is performed, for example, Japanese Patent Application No. 8-289373 (Japanese Patent Application Laid-Open No.
113199), there is a method in which a semiconductor substrate on which a sensor surface is formed is moved two-dimensionally by a light-transmitting XY stage, so that light is two-dimensionally scanned on the semiconductor substrate. However, in this method, since the sensor surface moves two-dimensionally, if the sample is not fixed to the liquid or the sensor surface, the sample may be displaced and accurate measurement may not be performed. .

As a method for improving the above method, there is a method in which all the irradiation light source systems are provided on an XY stage and the semiconductor substrate is two-dimensionally irradiated without moving the sensor. The structure becomes complicated, failures are likely to occur, and the load on the stage increases. As a result, the stage itself becomes large, and the overall configuration of the optical scanning type two-dimensional concentration distribution measuring device becomes large. is there.

It is also conceivable to perform optical scanning using a galvanometer mirror, an acousto-optic device, or the like. However, since the beam diameter of the illuminating light hitting the sensor surface is not constant, it is necessary to use an objective for precise measurement. There is a problem that a special optical system is used for the lens or software for correcting the measured value is required, so that a cost advantage is not necessarily obtained.

The present invention has been made in consideration of the above-mentioned matters, and has as its object to perform desired optical scanning without moving a sample, and to have a compact and inexpensive apparatus as a whole. An object of the present invention is to provide an optical scanning type two-dimensional concentration distribution measuring device.

[0008]

In order to achieve the above object, according to the present invention, a sensor surface is provided on one surface of a semiconductor substrate, and light from a light source is applied to the semiconductor substrate from the other surface side. In an optical scanning type two-dimensional concentration distribution measuring device configured to irradiate two-dimensionally, two linear stages whose movement directions are not parallel to each other are provided on the other surface side of the semiconductor substrate. In addition, a reflecting member for changing the course of light from the light source is provided, and by moving the linear stage, the semiconductor substrate is two-dimensionally irradiated with light from the other surface side.

In the optical scanning type two-dimensional concentration distribution measuring apparatus having the above-described structure, the semiconductor substrate can be irradiated with light in two-dimensional scanning without moving the sensor holding the sample. In addition, a single light source may be used, and the configuration for scanning the light from the light source two-dimensionally is simple. Therefore, the configuration for light irradiation is compact, and as a result, the optical scanning type two-dimensional density is obtained. The configuration of the distribution measuring device is also compact and inexpensive.

[0010]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show one embodiment of the present invention. First, FIG. 1 shows an optical scanning type pH as an example of the optical scanning type two-dimensional concentration distribution measuring apparatus of the present invention.
FIG. 2 is a diagram schematically illustrating a configuration of an image device.
Reference numeral 1 denotes a measuring device main body, which includes a sensor unit 2 and a light irradiation unit 3.

The sensor section 2 is configured as follows. That is, reference numeral 4 denotes a sensor, which is one surface (the upper surface in the illustrated example) of a rectangular substrate 5 made of a semiconductor such as silicon.
An SiO ₂ layer 6 and a Si ₃ N ₄ layer 7 as a sensor surface are sequentially formed by a method such as thermal oxidation or CVD, and the sensor surface 7 responds to hydrogen ions. Reference numeral 8 denotes a cell including the sensor surface 7 and provided around the sensor surface 7. The cell 8 is configured to accommodate a sample 9 such as a solution, and is made of an insulating material such as a synthetic resin.

Reference numerals 10 and 11 denote a counter electrode and a reference electrode (reference electrode) provided in the vicinity of the sensor surface 7, and both the counter electrode 10 and the reference electrode 11 are connected to a potentiostat 38 described later. 12 is the semiconductor substrate 5
Is connected to a potentiostat 38 via a current-voltage converter 39 and an operational amplifier circuit 40 described later.

Next, the configuration of the light irradiating section 3 will be described with reference to FIG. 2. The light irradiating section 3 is provided on the lower surface side of the sensor section 2, more specifically, on the sensor surface 7 of the semiconductor substrate 5. The laser light source 14 emits a laser beam 13 and the laser beam 13 is scanned in a two-dimensional direction. And an optical scanning unit 15.

The laser light source 14 includes a collimator, and the laser light 1 having a required beam diameter is reduced.
3 is provided so as to emit in the X direction parallel to one side of the sensor 4. The optical scanning unit 15 includes an X-axis scanning unit 16 that scans the laser beam 13 emitted by the laser light source 14 in the X direction over the entire length of the sensor 4 (semiconductor substrate 5) in the X direction. The laser beam 13 passes through 16 and scans over the entire length in the Y direction orthogonal to the X direction.

First, the structure of the X-axis scanning unit 16 will be described. Reference numeral 18 denotes a first base member, on the upper surface of which a guide groove 19 extends in the X direction, and extends along the guide groove 19. 1st moving on the surface of 1 base member 18
A linear stage 20 is provided. That is, the first linear stage 20 has a guide groove 19 at its bottom.
A nut portion 24 is provided on the upper surface of the nut portion 24, which extends in the X direction and is screwed with a ball screw 23 driven by a first pulse motor 22 rotating in both forward and reverse directions. Have. On the upper surface of the first linear stage 20, there is provided a first reflecting mirror 25 as a reflecting member for reflecting the laser light 13 emitted from the laser light source 14 and traveling straight in the X direction in the Y direction. 26 is the first
This is a mounting member for the pulse motor 22.

The configuration of the Y-axis scanning unit 17 will be described. A second base member 27 has two guide grooves 28a and 28b extending in the Y direction on the upper surface thereof. A second linear stage 29 that moves on the surface of the second base member 27 along 28a and 28b is provided. That is, the second linear stage 2
The second pulse motor 31 is provided at its bottom with protrusions 30a, 30b which engage with the guide grooves 28a, 28b, and at one end thereof is extended in the Y direction and rotates in both forward and reverse directions. Nut portion 33 that is screwed with a ball screw 32 driven by the motor. The laser light 1 from the first reflecting mirror 25 is provided on the upper surface of the second linear stage 29.
3 is provided with a second reflecting mirror 34 as a reflecting member that reflects the light 3 upward, that is, at a right angle to the lower surface of the semiconductor substrate 5. 35 is the second pulse motor 31
It is an attachment member.

The first pulse motor 22 and the second pulse motor 31 are connected to an optical scanning unit controller 36 (FIG. 1).
2), the first linear stage 20 and the second linear stage 29 move by a predetermined amount in the X direction and the Y direction, respectively. The optical scanning unit 15 is set as follows in order to two-dimensionally scan the entire back surface (lower surface) of the semiconductor substrate 5 with the laser light 13 from the laser light source 14. I have. That is, the plane of the first reflecting mirror 25 is set to be larger than the beam diameter of the laser light 13. Also, the second reflecting mirror 34
The first reflecting mirror 25 provided on the first linear stage 20 that moves at least in the X direction while having a length equal to or longer than the length of the semiconductor substrate 5 in the Y direction is at least in the X direction of the semiconductor substrate 5. The length is configured to be movable.

Referring again to FIG. 1, reference numeral 37 denotes a control box for controlling the sensor section 2 and the light irradiating section 3 and sending a signal from the sensor section 2 to a computer 42 (to be described later) as an arithmetic control section. A potentiostat 38 for applying an appropriate bias voltage to the semiconductor substrate 5; a current-voltage converter 39 for converting a current signal extracted from the ohmic contact 12 formed on the semiconductor substrate 5 into a voltage signal; An operational amplifier circuit 40 to which a signal from the voltage converter 39 is input, which transmits and receives signals to and from the operational amplifier circuit 40, the laser light source 14 and the optical scanning unit controller 3.
Interface board 4 that outputs control signals for 6
1 and so on.

Reference numeral 42 performs various controls and calculations,
A computer as an image output device having image processing and output functions; an input device 43 such as a keyboard; a display device 44 such as a color display;
5 is provided.

The case where the hydrogen ion concentration (pH) of the solution is measured by using the optical scanning type two-dimensional concentration distribution measuring device having the above-described configuration will be described. The solution 9 is put in the cell 8.
Thus, the solution 9 comes into contact with the sensor surface 7. Then, the counter electrode 10 and the reference electrode 11 are immersed in the solution 9.

In the above state, a DC voltage from the potentiostat 38 is applied between the comparison electrode 11 and the ohmic contact 12 so that a depletion layer is generated in the semiconductor substrate 5, and a predetermined bias is applied to the semiconductor substrate 5. Apply voltage. In this state, an alternating photocurrent is generated in the semiconductor substrate 5 by intermittently irradiating the semiconductor substrate 5 with the laser light 13 at a constant period (for example, 5 kHz). The intermittent irradiation of the laser light 13 is performed when a control signal of the computer 42 is input via the interface board 41. The photocurrent is a value reflecting the pH of the solution 9 in contact with the sensor surface 7 at a point facing the irradiation point of the semiconductor substrate 5, and by measuring the value, the pH value at this portion is calculated. You can know.

Further, the light scanning unit control device 36
By scanning the laser beam 13 two-dimensionally in the X and Y directions, the semiconductor substrate 5 is irradiated with the laser beam 13 so as to be scanned in the two-dimensional direction, and the position signal (X, Y) in the solution 9 is obtained. Then, a two-dimensional image representing pH is displayed on the screen of the display device 44 based on the AC photocurrent value observed at the place.

The laser beam 13 is scanned by, for example, fixing the second linear stage 29 and moving only the first linear stage 20 in the X direction.
Can be scanned with respect to the semiconductor substrate 5 in the X direction. Each time the first linear stage 20 performs one scan in the X direction, the second linear stage 29 is moved in the Y direction by one step of the measurement width, whereby the sensor 4
The entire surface can be scanned.

The laser beam 13 is collimated so as to have a required beam diameter. The maximum value of the optical path difference of the laser beam 13 up to the sensor 4 is, for example, 25 mm. 35.36mm for corners
(= 25 mm × √2), and the influence of the natural spread of the laser beam 13 is such that sufficient accuracy can be ensured if the measurement resolution is about 100 μm, for example.

The present invention is not limited to the above embodiment, but can be implemented in various modifications.
The moving directions of the first linear stage 20 and the second linear stage 29 do not have to be orthogonal to each other.
At an arbitrary angle such as ° or 60 °, that is, the first
It is sufficient that the moving directions of the linear stage 20 and the second linear stage 29 are not parallel to each other. In consideration of the control signals for the linear stages 20 and 29 and the processing of the obtained measurement signals, the angle between the moving directions of the linear stages 20 and 29 is 45 ° or 6 °.
0 ° and 90 ° are preferred.

The first linear stage 20 and the second linear stage 20
The linear stage 29 may be driven by a linear motor or an ultrasonic linear motor, as long as it can identify a measurement point on the sensor 4 by detecting a moving speed or position information.

The order of scanning in the first linear stage 20 and the second linear stage 29 is arbitrary, and both may be driven simultaneously.

Further, the control of the first linear stage 20 and the second linear stage 29 may be performed by an independent controller, or remote scanning may be performed using communication means such as the Internet.

The reflecting members 25 and 3 are used as reflecting members.
Instead of 4, a prism may be used.

Further, the optical scanning type two-dimensional concentration distribution measuring apparatus of the present invention can measure ion concentrations other than pH by modifying the sensor surface 7 with an appropriate response member.

[0031]

In the optical scanning type two-dimensional density distribution measuring apparatus of the present invention, light is two-dimensionally scanned on the semiconductor substrate on the back side of the sensor by using two linear stages. There is no need to move the sample with the sensor. Therefore, the measurement accuracy for a sample that is difficult or unfixed on the sensor surface is improved.
Since only the reflection member is provided on the linear stage, the load is small, the structure is simpler than that of the conventional light transmission type XY stage, and the cost is low.

Since the incident angle of light incident on the semiconductor substrate on the back side of the sensor is constant regardless of the irradiation point, a special optical system is not required as compared with the case where a galvanometer mirror or the like is used. And the configuration is simplified and the cost is reduced accordingly.

As described above, according to the present invention, it is possible to obtain an optical scanning type two-dimensional density distribution measuring apparatus which can perform a predetermined measurement reliably, and has a compact and inexpensive structure as a whole.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an optical scanning type two-dimensional density distribution measuring apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of a main part of the device.

[Explanation of symbols]

5 Semiconductor substrate, 7 Sensor surface, 13 Light, 14 Light source, 20, 29 Linear stage, 25, 34 Reflecting member.

Claims (1)

[Claims] An optical scanning type device having a sensor surface on one surface of a semiconductor substrate and configured to two-dimensionally irradiate light from a light source to the semiconductor substrate from the other surface side. In the two-dimensional concentration distribution measuring device, two linear stages whose movement directions are not parallel to each other are provided on the other surface side of the semiconductor substrate, and on these linear stages, a reflecting member that changes a course of light from the light source is provided. A light scanning type two-dimensional density distribution measuring apparatus, wherein the light is two-dimensionally irradiated on the semiconductor substrate from the other surface side by moving the linear stage.