JPS63289876A - High-speed response optical position detector - Google Patents

Abstract

PURPOSE:To realize a high-speed response without deteriorating the resolving power of a position by a method wherein a second semiconductor layer is constituted by a number of linear semiconductor layers which cross at right angles mutually. CONSTITUTION:A p-type semiconductor resistance layer 2 is formed on an n-type high-resistance semiconductor substrate 1; electrodes 3, 4 are formed on the p-type semiconductor resistance layer. In addition, the p-type semiconductor resistance layer is parallel to directions of the electrodes 3 and 4; one high-resistance stripe 21 and a number of low-resistance stripes 22 crossing at a right angle to the stripe 21 are formed; the stripe 21 and the stripes 22 are connected electrically. Accordingly, when the light is incident, a photoproduction charge generated at an incident position reaches the stripe 21 via the low-resistance stripes 22 as a photoelectric current which is proportional to the incident energy of the light. The photoelectric current is divided in such a way that it is inversely proportional to a resistance value from an arrival point at the stripe 21 to the electrodes 3 and 4; it can be taken out from the electrodes 3 and 4 as an output. By this setup, it is possible to respond to a high-speed modulated light source at high speed without deteriorating the resolving power of a position.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical position detector made of a semiconductor element that detects the position of incident light, and in particular enables high-speed response without reducing position resolution. This invention relates to a high-speed response optical position detector.

[Conventional technology]

In general, optical position detectors (hereinafter referred to as PSD) do not perform scanning as in television picture tubes or solid-state picture elements, but rather detect the lateral PSD on the semiconductor surface.
This is a device that uses photo effect to detect photogenerated charges generated at the position of incident light as position information, and is widely used in various fields.

FIG. 2 is a diagram showing the cross-sectional structure of the PSD, in which 1 is an n-type high-resistance semiconductor substrate, 2 is a p-type semiconductor resistance layer, 3 and 4 are electrodes, 5 is an n'' layer, 6 is a light incident position, and 7 indicates a common electrode.

In the figure, a p-type semiconductor resistor N2 and an n+ layer 5 are uniformly formed on each surface of an n-type high resistance semiconductor substrate 1,
A pair of electrodes 3 and 4 for signal extraction are provided on both sides of the p-type semiconductor resistance layer 2.

In such a configuration, let the distance between the electrodes 3 and 4 be RL, the resistance be RL, the distance from the electrode 3 to the light incident position 6 be X, and the resistance at that portion be Rll. The photogenerated charge generated at the light incident position reaches the p-type semiconductor resistance layer 2 as a photocurrent proportional to the incident energy of the light, and is divided so as to be inversely proportional to the resistance value up to each electrode.
and 4. If the photocurrent generated from the incident light is Io, and the currents taken out from electrodes 3 and 4 are la and Im, then la = io ・(RL RX ) / RL
.

1, -1゜・RX/RL ・・・・・・・・・
...(1). The p-type semiconductor resistance layer 2 is uniform,
If length and resistance value are proportional, equation (1) becomes IA-
1°・(L-X)/L.

+l-1°・X/L 6 1A and 1. Find the ratio of Ia
/Im −(L−X)/X−L/X−1, and Ia/
From the value of In, the incident position of light can be known regardless of the incident energy.

PS where the incident position of light can be determined in this way
In D, in order to increase the positional resolution, it is necessary to increase the resistance between opposing electrodes. It is known that this positional resolution is proportional to the signal-to-noise ratio of the PSD, where the signal is proportional to the intensity of incident energy, and the noise is inversely proportional to the resistance between the electrodes.

Fig. 3 is a diagram showing the structure of a conventional PSD with high resistance between the electrodes, Fig. 3 (a) is its plan view, Fig. 3 (b) is its sectional view in the The same numbers as in Figure 2 indicate the same contents. Note that 11 is a p-type semiconductor resistance layer.

In the figure, p-type semiconductor resistors l111 are formed in stripes on one side of an n-wall high-resistance semiconductor substrate l.

P-type semiconductor resistance F! The resistance between electrodes 3 and 4 is increased by forming Ill into stripes.

In such a configuration, when light is incident, the photogenerated charge generated at the light incident position due to the photoelectric effect becomes a photocurrent that is proportional to the incident energy of the light, and is inversely proportional to the resistance value up to electrodes 3 and 4. and is taken out from the electrodes 3 and 4 through the stripe 11.

In this case, compared to the resistance when the p-type semiconductor resistance layer is uniformly provided in a planar shape as shown in FIG. We are working to improve this.

[Problems to be solved by the invention]

However, when using PSD, P
The dark current of the SD and the current due to the background light mix, which tends to cause measurement errors.Therefore, it is necessary to use a PSD with low dark current, use it without background light, and increase the incident energy from the light incidence position. . On the other hand, as a method to avoid errors caused by these noises, the DC light source is
By turning off N1 or intermittently emitting or oscillating an LED or laser, and detecting it in synchronization with this, the DC component is often suppressed and peak hold is performed to perform position calculations. In this case, PSD is required to respond quickly to a light source that is modulated at high speed. Since the response speed is inversely proportional to the product of capacitance and resistance, it is desirable that the inter-electrode resistance be small in order to increase the response speed.To achieve this, in the case of the PSD shown in Fig. 3, it is necessary to Although it becomes necessary to reduce the resistivity over the entire area, this results in a degradation of the positional resolution and is not a desirable solution.

The present invention is intended to solve the above-mentioned problems, and it is an object of the present invention to provide a high-speed response optical position detector that can realize high-speed response without deteriorating the position resolution.

[Means for solving problems]

To this end, the high-speed response optical position detector of the present invention includes a semiconductor layer of a second conductivity type formed on the surface of a semiconductor substrate of a first R conductivity type, and a pair of position detection signals facing each other on the semiconductor layer of the second conductivity type. For output! In an optical position detector in which the position of a particle beam incident from the surface of a semiconductor layer of the first or second conductivity type is calculated from the output of the electrode, the second semiconductor layer has a plurality of particles perpendicular to each other. It is characterized by being composed of linear semiconductor layers.

[Effect]

The high-speed response optical position detector of the present invention includes a PSD in which a striped resistance layer of a second electric shock type is formed on a high-resistance semiconductor substrate of a first conductivity type, and further stripes of a second conductivity type that are orthogonal to each other. By forming such a resistive layer, the position of incident light can be measured with increased responsiveness without reducing positional resolution.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a high-speed response optical position detector according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view, with the same number as in FIG. 2. indicate the same content. Note that 21 and 22 are striped resistance layers.

The fast-response optical position detector of the present invention has a p-type semiconductor resistance layer 2 formed on an n-type high-resistance semiconductor substrate 1, as in the conventional case, and
Electrodes 3 and 4 are provided on the p-type semiconductor resistance layer, and the p-type semiconductor resistance layer is parallel to the direction of the electrodes 3 and 4, and has one high-resistance stripe 21 and a stripe 2.
1, a large number of low resistance stripes 22 are formed, and the stripes 21 and 22 are electrically connected.

In such a configuration, when light is incident, photogenerated charges generated at the incident position reach the stripe 21 via the low resistance stripe 22 as a photocurrent proportional to the incident energy of the light. Then, it is divided in inverse proportion to the resistance value from the reaching point of the stripe 21 to the electrodes 3 and 4, and can be taken out as an output from the electrodes 3 and 4.
From this detected value, the light incident position can be determined as described above.

By the way, as mentioned above, noise is inversely proportional to the inter-electrode resistance, but in the case of Fig. 3, multiple stripes are inserted in parallel between the electrodes, so in order to achieve the same inter-electrode resistance as in the present invention, it is necessary to , the resistance of one stripe is 0, which is the resistance of stripe 21 of the present invention times the number of stripes.
For example, if the number of stripes is 10 and the interelectrode resistance is 100Ω, the resistance per stripe is IMΩ. Then, due to the incidence of minute spot light, the current flows through one stripe or two adjacent stripes, so the resistance value at this time is IMΩ or 50
0 to Ω, and as a result, the time constant becomes large and the response becomes poor.

On the other hand, in the case of the present invention, the resistance of the stripe 21 in order to make the inter-electrode resistance 100.OMEGA. is only 100.OMEGA., so that the responsiveness can be improved without deteriorating the positional resolution.

Note that since the stripe 22 is for collecting photogenerated charges,
It is not related to the position resolution, and the smaller the resistance, the better.
Responsiveness improves when the width is two to three orders of magnitude smaller than the stripe 22.

Further, in the above embodiment, a p-type resistance layer is provided on the surface of the n-type high resistance substrate, and a detection electrode is provided on the p-type resistance layer, but the relationship between n-type and p-type may be reversed. stripe 2
1 does not necessarily have to be one.

〔Effect of the invention〕

As described above, according to the present invention, by applying a PSD composed of a striped high resistance layer parallel to the electrode direction and a large number of striped low resistance layers perpendicular to the electrode direction, the positional resolution is degraded. It is possible to respond quickly to a high-speed modulated light source without having to do so. Further, according to the results actually obtained with a PSD having an effective light-receiving area of 1 m x 3 cranes, the response time of the conventional PSD was 2.5 μsec, whereas the PSD of the present invention was able to shorten the response time to 1 μsec.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a high-speed response optical position detector according to the present invention, in which (a) is a plan view, (b) is a cross-sectional view, and FIG. 3 is a sectional view of a conventional PDS, and the same figure (a) is a plan view, and the same figure (
B) is a sectional view taken along the line XX. DESCRIPTION OF SYMBOLS 1... High resistance semiconductor substrate, 2... P-type semiconductor resistance layer, 3.4... Electrode, 5... N+ layer, 6... Light incident position, 7... Common electrode, 11.21...Stripe parallel to the electrode direction, 22 is a stripe perpendicular to the electrode direction. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masaaki Hirukawa Figure 3 (In (U:J)

Claims (2)

[Claims] (1) A semiconductor layer of a second conductivity type is formed on the surface of a semiconductor substrate of a first conductivity type, a pair of opposing position detection signal output electrodes are formed on the semiconductor layer of the second conductivity type, and the first, Alternatively, in an optical position detector that calculates the position of a particle beam incident from the surface of a second conductivity type semiconductor layer from the output of the electrode, the second semiconductor layer is composed of a number of linear semiconductor layers orthogonal to each other. A high-speed response optical position detector characterized by: (2) The multiple linear semiconductor layers orthogonal to each other are
2. The high-speed response optical position detector according to claim 1, comprising a semiconductor layer having different resistivities in a direction parallel to and perpendicular to the direction of the opposing electrodes.