JP2676251B2 - Temperature controller for semiconductor devices - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a temperature control device for a semiconductor device, which utilizes the property of a thin film heat sink / heater capable of high-speed and highly accurate temperature control. This control device is used for temperature control of semiconductor elements such as semiconductor lasers, photodiodes, and ICs.For example, when used for semiconductor lasers, a light source that can modulate or stabilize the frequency and light intensity of laser light by temperature control is used. realizable.

[Prior Art] In a semiconductor laser, both the frequency and the light intensity of the laser light fluctuate due to fluctuations in the ambient temperature, and the fluctuation rate is a frequency of minus several GHz / K and a light intensity of minus several tens.
It is μW / K.

In the case of a photodiode, the sensitivity has temperature dependence. As described above, various temperature-dependent phenomena exist in the semiconductor element, and therefore various temperature control devices have been devised and used.

In the conventional technique, the temperature control of the semiconductor element is mainly to stabilize at an arbitrary temperature, and the temperature has not been changed. Since a bulk Peltier element is used, when controlling temperature with high accuracy, the element shape inevitably becomes large, and therefore the value of heat capacity also becomes large, and the thermal response time is from a few seconds to a few minutes. This is because it is also impossible to change the temperature practically. This was the same even when using a multi-stage Peltier device. Further, although an injection current of several amperes (A) or more is required to drive the element, the larger the injection current, the larger the current fluctuation, and the current fluctuation causes the deterioration of the temperature control accuracy.

[Problems to be Solved by the Invention] Therefore, in the present invention, the following problems in the conventional technique are solved by controlling the temperature of a semiconductor element at high speed and with high accuracy by a thin film heat-absorbing body having a small heat capacity. The purpose is to do.

If the conventional temperature control element is used to control the temperature of the semiconductor element, (1) a temperature control element having a larger heat capacity is required to perform highly accurate control, and the apparatus becomes large.

(2) When a temperature control element having a large heat capacity is used, the thermal response time takes several seconds to several minutes, and high-speed control cannot be performed.

(3) In order to drive a temperature control element having a large heat capacity, it is generally necessary to inject a precisely controlled current of about several amperes (A), and a large current source is required. there were.

(4) The larger the injected current, the larger the current fluctuation, which deteriorates the accuracy of temperature control.

[Means and Actions for Solving the Problems] In the present invention, in order to solve the above problems, a temperature control element capable of changing the ambient temperature of a semiconductor element by a large temperature and a thin film absorbing / heating element having a high thermal response are provided. This is realized by controlling with a two-stage temperature control device. Especially as the second stage element, the thermoelectric effect (Peltier effect) that can change the heat absorption and heat generation in the direction of current flow is adopted.
A structure is adopted in which a bonded body of conductors having different conductivity having this effect is formed of a thin film, and the bonded body is brought into contact with a semiconductor whose temperature is to be controlled.

(1) Since the thin film absorbing / heating element is very small, the temperature control device can be downsized.

(2) Since the heat capacity of the thin-film absorbing / heating element is very small, the thermal response time is as fast as 10 ⁻⁴ seconds or less, so that the ambient temperature of the semiconductor element can be controlled as fast as that.

(3) Since the thin film absorption / heating element can be driven with an injection current of about several tens of milliamperes (mA), the current source can be downsized.

(4) Since the injection current into the thin film absorption / heating element can be small, the current fluctuation is small and the temperature control accuracy can be improved.

Example FIG. 1 shows the components of the present invention. On the upper surface of the temperature control element 1, a thin film heat sink 3 is provided via an electrical insulator layer 2.

The thin film heat sink 3 is made of a conductor having different conductivity, and is composed of, for example, a p-type semiconductor or semi-metal film 4, an n-type semiconductor or semi-metal film 5, and a pn junction 6. Current supply terminals 7 and 7a are attached to both ends thereof.

A semiconductor element whose temperature is desired to be controlled, for example, a semiconductor laser (not shown) is placed on the upper surface of the thin film absorption / heating element 3.

Examples of the material of the thin film heat absorption / heating element 3 include Bi ₂ Te ₃ alloy, PbTe, Bi—Sb alloy, and Si—Ge alloy, which have a large Seebeck coefficient. By adjusting the composition of these materials, it becomes a p-type conductor (semiconductor or semimetal) and an n-type conductor (semiconductor or semimetal), and these are deposited on the substrate by, for example, the CVD method or the vapor deposition method. Deposit on thin film. A metal is deposited between the p-type conductor thin film 4 and the n-type conductor thin film 5 to form a pn junction. When a current is injected from the n-type semiconductor thin film 5 into the p-type semiconductor thin film 4 due to the Peltier effect
Heat is generated in the pn junction 6 and heat is absorbed when a current is injected in the opposite direction. The temperature of the semiconductor element is controlled by this heat absorption and heat generation.

Next, a case where the present invention is actually used will be described. As described in the section of the conventional technique, the laser light intensity of the semiconductor laser has a temperature dependence of about minus several tens of μW / K. Therefore, FIG. 2 shows an embodiment in which the present invention is applied to a light intensity stabilizing light source which stabilizes the light intensity by negatively feeding back the fluctuation of the light intensity to the temperature by utilizing this dependency.

A semiconductor laser terminal 9 is installed above the semiconductor laser 8, and a pole plate 10 and the other semiconductor laser terminal 9a are installed below the semiconductor laser 8, and a current I from the semiconductor laser current source 11 to the semiconductor laser terminals 9 and 9a. _The semiconductor laser 8 emits laser light by injecting _s . A laser beam from the semiconductor laser 8 is split into two directions by a beam splitter 12. The path of light is shown by an arrow consisting of two solid lines. One of the laser light intensities branched by the beam splitter 12 is converted into an output voltage V by a photoelectric converter 13. Since the output voltage V is proportional to the light intensity of the laser light, the variable DC voltage source 14
By comparing the reference voltage V _s with the output voltage V, the variation ΔP of the light intensity can be detected. The voltage difference (V _s −V) between the reference voltage V _s and the output voltage V is detected by the comparator 15, and the comparator 15
The output signal from is negatively fed back to the current source 16 for the thin film absorption / heating element. The current source 16 for thin-film heat-absorbing body detects this negative feedback signal, injects a current corresponding to the negative feedback signal into the thin-film heat-absorbing body 3, and controls the temperature of the semiconductor laser 8 by heat-absorbing heat from the thin-film heat-absorbing body 3. . That is, the ambient temperature of the semiconductor laser 8 is controlled so that the variation ΔP of the light intensity becomes zero. An electrically insulating substrate 17 is placed between the thin film heat absorbing and heating elements 3 of the semiconductor laser 8 in order to prevent a short circuit of the current flowing therethrough. Although the thin-film heat-absorbing body 3 can control a minute temperature change at high speed, it is difficult to make a large temperature change. The control element 1 is mounted, and the temperature control element 1 performs large temperature control. That is, the temperature control element 1 brings the temperature close to the temperature to be set up to about ± several mk, and the thin film absorption / heating element 3 finely adjusts the temperature. At this time, the thermal response time of the temperature control element 1 is very slow, from a few seconds to a few minutes, but that of the thin film absorption / heating element 3 is 10 ^-4 seconds or less, so the semiconductor laser is as fast as that. Temperature control.

FIG. 3 shows the actually measured light intensity of the light intensity stabilizing light source.

(A) is a time-dependent change of ambient temperature T and light intensity P of a semiconductor laser when a conventional bulk Peltier device is used and (b) is the temperature control device of the present invention. In (a), since the ambient temperature T cannot be controlled at high speed, short-period noise remains in the light intensity P. However, in (b), since the ambient temperature T can be changed in a short time, most of the noise of the light intensity P can be removed. That is, in (b), P _F showing the change over time of the light intensity in the non-controlled state could be brought to the P state by applying the temperature control device of the present invention.
Comparing this with the conventional technique of (a), the effect is remarkable. The curve T in (a) and (b) represents the temperature of the semiconductor laser. As is apparent from this, in the present invention, the temperature change of the semiconductor element quickly follows.

A semiconductor laser is an element with two inputs (ambient temperature, injection current) and two outputs (frequency, light intensity) that can control the frequency and light intensity of laser light by injection current in addition to ambient temperature. However, since the conventional technology cannot perform high-speed temperature control, for example, in the case of "Frequency-stabilized light source" by the same applicant (Japanese Patent Application No. 1-53722), the temperature was fixed to a constant value. It has been used as an element with one input (injection current) and one output (frequency). However, by using the above-described embodiment, it is possible to control the light intensity with temperature and the frequency with the injection current, and to stabilize it as an example.

[Effects of the Invention] As described above, the temperature control device for a semiconductor device according to the present invention uses a thin film absorbing / heating element in combination with a conventional temperature control device as a temperature control device, thereby providing the following. It has such an inherent effect.

(1) The thin film absorbing / heating element having a small heat capacity was able to sufficiently cope with a semiconductor laser that requires high speed such as temperature control.

(2) Since a temperature control element having a large heat capacity is not required even during highly accurate temperature control, the device can be downsized.

(3) Since the injection current of the thin film absorption / heating element is several tens of milliamperes (mA) or less, a small current source can be used.

(4) Since the injected current can be small, the fluctuation of the current generated from the current source is also small and the deterioration of the temperature control accuracy due to the fluctuation of the current is small. Therefore, the temperature control can be realized with high accuracy of 10 ^-2 mk or less. .

[Brief description of the drawings]

FIG. 1 shows a "temperature control device for semiconductor elements" according to the present invention.
FIG. 2 is a diagram illustrating a configuration of one embodiment. FIG. 2 is a diagram showing a configuration of an embodiment of a light intensity stabilizing light source device utilizing the present invention. FIG. 3 shows the ambient temperature T of the semiconductor laser when the conventional bulk-shaped Peltier device is used for the light intensity stabilizing light source described in the embodiment (a) and when the temperature control device according to the present invention is used (b). And shows the change with time of the light intensity P. Further, P _F is the light intensity without temperature control. In the figure, 1 is a temperature control element, 2 is an electrical insulator layer,
Reference numeral 3 is a thin film heat sink, 7 and 7a are current supply terminals, 8 is a semiconductor laser, 9 and 9a are semiconductor laser terminals, 10 is an electrode plate, 11
Is a current source for a semiconductor laser, 12 is a beam splitter, 13 is a photoelectric converter, 14 is a DC voltage source, 15 is a comparator, 16 is a current source for a thin film absorption / heating element, 17 is an electrically insulating substrate, and 18 is temperature control. The respective current sources for the device are shown.

Claims (1)

(57) [Claims] 1. A temperature control element (1), an electrical insulator layer (2) provided on the surface of the temperature control element, and a semiconductor element to be temperature-controlled on the electrical insulator layer. A thin film absorbing / heating element (3) having a surface and made of different kinds of conductors, and current supply terminals (7, 7) provided at both ends of the thin film absorbing / heating element.
7a) A semiconductor element temperature control device comprising: