JPH0669148A - Heater - Google Patents

Abstract

PURPOSE:To improve uniformity in the overall temperature distribution of an object to be heated, e.g. a semiconductor wafer, being heated through irradiation with infrared ray from a lamp light source. CONSTITUTION:In a heating system where infrared ray from a lamp light source 1 reflects on a reflector 4 and transmits through a silicon diffuser 5 to impinge uniformly on the entire semiconductor wafer(heating object) 3, a prism 10a is arranged in a region where an infrared ray deviated from the semiconductor wafer 3 and not contributes to heating will pass in order to diffract such infrared rays and concentrically irradiates the end 3b of the semiconductor wafer 3 thus locally heating the end part 3b. Consequently, temperature drop due to dissipation of heat from the end part 3b is suppressed, the end part 3b is heated at the same temperature as the central part 3a, resulting in heat treatment at uniform temperature over the entire semiconductor wafer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for heating an object to be heated such as a semiconductor wafer with a uniform temperature distribution by means of infrared rays from a lamp light source, and is used in a step of impurity diffusion and diffusion of a semiconductor wafer.

[0002]

2. Description of the Related Art As a heating device, for example, a lamp annealing device for a semiconductor wafer used for injecting and diffusing impurities ion-implanted into a semiconductor wafer is shown in FIG. There are devices that use a mold chamber (6) and devices that use a horizontal quartz chamber (7) as shown in FIG.

The lamp annealing apparatus shown in FIG. 5 turns on a lamp light source (1) such as an arc lamp arranged at the focal position of a retro-gutter-shaped reflector (4), and reflects its infrared rays by the reflector (4). , Heating the semiconductor wafer (3) located directly below the reflector (4). Reflectors (4)
Is installed directly above the quartz chamber (6), and a quartz diffusion plate (5) is placed between the two. A semiconductor wafer (3) held by a quartz stage (8) is placed in a chamber (6) in parallel with a diffusion plate (5). Three quartz pins (8a) are projectingly provided on the stage (8), and the tip of each quartz pin (8a) supports the semiconductor wafer (3). The stage (8) is supported by the chamber base (9) so that it can move in and out freely.

When the lamp light source (1) is turned on while keeping the inside of the chamber (6) in a gas atmosphere such as a nitrogen gas flow, a part of the infrared rays passes through the diffuser plate (5) and the semiconductor wafer ( The remaining infrared rays are reflected by the reflector (4), transmitted through the diffuser plate (5), and are irradiated almost vertically on the semiconductor wafer (3). Infrared rays of the lamp light source (1) are evenly irradiated and absorbed in the entire surface of the semiconductor wafer (3), and the entire semiconductor wafer (3) is heated with a substantially uniform temperature distribution. As a whole, the impurity indentation diffusion proceeds.

In the lamp annealing apparatus shown in FIG. 6, a lamp light source (2) such as a tungsten lamp is arranged around the outer periphery of the horizontal chamber (7). A semiconductor wafer (3) supported at three points by a stage (8 ') is placed in a chamber (7). When the lamp light source (2) is turned on with the inside of the chamber (7) kept in a predetermined gas atmosphere, the lamp light source (2)
Of the semiconductor wafer (3) penetrates through the chamber (6) and is uniformly irradiated on the surface of the semiconductor wafer (3).
Is heated with the atmosphere in a substantially uniform temperature distribution.

[0006]

In the lamp annealing apparatus of FIG. 5, the reflector (4) and the diffuser plate (5) are so arranged that the infrared rays of the lamp light source (1) are uniformly irradiated on the entire semiconductor wafer (3). ) Is used, there is a low temperature difference between the central portion (3a) and the peripheral edge portion (3b) of the semiconductor wafer (3) at the edge portion (3b). This semiconductor wafer (3)
The cause of the variation in the temperature distribution of the semiconductor wafer (3)
The end portion (3b) of the semiconductor wafer (3b) has a larger amount of heat radiation, and the end portion (3b) of the semiconductor wafer (3) is farther from the lamp light source (1) than the central portion (3a), and the end portion (3b) This is because the amount of infrared light radiated to the area is less than that in the central part (3a).

As a result, when the semiconductor wafer (3) is heated to perform impurity push-in diffusion, the temperature of the end portion (3b) of the semiconductor wafer (3) becomes insufficient, and the impurity push-in diffusion at the end portion (3b) occurs. There was a problem that the progress was delayed and the quality of a plurality of semiconductor elements formed on the semiconductor wafer (3) varied.

Further, in the case of the lamp annealing apparatus of FIG.
The whole semiconductor wafer (3) is irradiated with infrared rays on average, but the heat radiation amount at the peripheral edge portion (3b) of the semiconductor wafer (3) becomes larger than that at the central portion (3a), and as a result, the semiconductor wafer (3 Regarding the temperature of 3), the temperature of the end portion (3b) is lower than that of the central portion (3a). Therefore, similarly to the above, there is a problem that the quality of the semiconductor elements on the semiconductor wafer (3) varies.

Therefore, the object of the present invention is to
It is an object of the present invention to provide a lamp annealing apparatus that heats the entire semiconductor wafer more uniformly to reduce variations in the quality of semiconductor elements formed on the semiconductor wafer.

[0010]

DISCLOSURE OF THE INVENTION The present invention is an apparatus for uniformly irradiating infrared rays from a lamp light source to a whole object to be heated (semiconductor wafer) to heat the object to be heated, and a lamp is provided at the end of the object to be heated by another lamp. The above object is achieved by additionally providing local heating optical means for irradiating the infrared rays of the light source in a concentrated manner.

The local heating optical means is a prism that refracts infrared rays from the lamp light source and irradiates the heated object end portion, or a reflecting mirror that reflects the infrared ray from the lamp light source to the heated object end portion. Is practically desirable.

Further, according to the present invention, in an apparatus for heating an object to be heated by uniformly irradiating the object to be heated with infrared rays from a lamp light source, the infrared light of the lamp light source is heated near the end of the object to be heated. The above object is also achieved by disposing a heat storage member having a large heat capacity.

[0013]

[Function] For an object to be heated which is uniformly irradiated with infrared rays from the lamp light source, the amount of infrared rays that is more intensively applied to the end of the object to be heated is increased by a prism or a reflecting mirror. By setting a value that compensates for the amount of temperature decrease due to heat radiation during normal infrared heating of the end portion, the entire body of the object to be heated is heated with a uniform temperature distribution without the temperature decrease at the end portion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to FIGS. 1 to 3 show the first to third embodiments applied to the lamp annealing apparatus of FIG. 5, and FIG. 4 shows the fourth embodiment applied to the lamp annealing apparatus of FIG. 5 and FIG. 6 of each of these embodiments, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted.

The lamp annealing apparatus shown in each of the embodiments of FIGS. 1 to 3 is a semiconductor wafer in which infrared rays from the lit lamp light source (1) are reflected by a reflector (4) and transmitted through a diffuser plate (5). Irradiate almost perpendicularly to (3) to heat the entire semiconductor wafer (3) on average. The difference between these devices and the conventional device is that a local heating optical means (10) for irradiating a part of infrared rays of the lamp light source (1) to the end (3b) of the semiconductor wafer (3) in a concentrated manner is additionally provided. That is.
Three specific examples of the local heating optical means (10) are shown in FIGS.
It is shown in.

The local heating optical means (10) shown in the lamp annealing apparatus of the first embodiment of FIG. 1 is a diffusion plate (5).
It is the prism (10a) installed above. Prism (10
(a) is fixedly arranged at a predetermined inclination angle, slightly outside the end (3b) of the semiconductor wafer (3).

In the apparatus shown in FIG. 1, the semiconductor wafer (3) is heated as follows. Infrared rays from the lamp light source (1) directly pass through the diffuser plate (5), and also reflect off the reflector (4) and then pass through the diffuser plate (5), so that the semiconductor wafer (3) can be transferred to the same device as in FIG. Heat to. At the same time, a part of the infrared light reflected by the reflector (4) is incident on the upper surface of the prism (10a), refracted, exits from the lower surface, passes through the diffuser plate (5), and passes through the semiconductor wafer (3). The end (3b) is irradiated intensively. Further, in this way, the infrared rays are intensively applied to the end portion (3b) of the semiconductor wafer (3),
A prism (10a) is arranged.

If there is no prism (10a), the semiconductor wafer (3) is heated as in the apparatus shown in FIG. 5, and the temperature of the end portion (3b) becomes lower than that of the central portion (3a). However, with the prism (10a), the edge (3
If infrared rays are concentrated excessively on b), the end portion (3
The temperature of b) rises. Therefore, by supplementing the prism (10a) with an amount of infrared rays commensurate with the temperature decrease of the end portion (3b) of the semiconductor wafer (3) during normal heating, the central portion (3a) and the end portion (3a) of the semiconductor wafer (3) are The whole of 3b) is heated at a uniform temperature.

Most of infrared rays refracted by the prism (10a) and applied to the end (3b) of the semiconductor wafer (3) are
When there is no prism (10a), it is a so-called useless infrared ray that comes off the semiconductor wafer (3) and hardly contributes to heating of the semiconductor wafer (3). This useless infrared ray is effectively utilized by the prism (10a) for heating the semiconductor wafer (3). as a result,
The effective utilization rate of infrared rays of the lamp light source (1) is increased, and the waste of power is reduced. This also applies to the following second to fourth embodiments.

In the case of the apparatus shown in FIG. 1, since the prism (10a) is arranged in a clean space surrounded by the reflector (4) and the diffusion plate (5), the prism (10a) becomes cloudy and the refractive index changes. No worries and easy maintenance.

The local heating optical means (10) in the lamp annealing apparatus shown in the second embodiment of FIG. 2 is a reflecting mirror (10b) arranged inside the chamber (6).
The reflecting mirror (10b) has an end portion (3) below the end portion (3b) of the wafer (3) supported by the wafer stage (8).
It is arranged obliquely toward the lower surface of b). Reflector (10b)
Reflects infrared rays reflected from the reflector (4), transmitted through the diffuser plate (5) and near the edge of the semiconductor wafer (3) toward the lower surface of the edge (3b) of the semiconductor wafer (3), Locally heat the end (3b).

The apparatus shown in FIG. 2 irradiates infrared rays from the lamp light source (1) onto the entire upper surface of the semiconductor wafer (3) in the same manner as the apparatus shown in FIG. 5 to heat the semiconductor wafer (3), and at the same time, the semiconductor wafer (3) is heated during the normal heating. Infrared rays leaving the wafer (3) are reflected by the reflecting mirror (10b) and concentratedly irradiate the end portion (3b) of the semiconductor wafer (3) to locally heat the end portion (3b). Also in this case, if the reflection mirror (10b) compensates for the amount of infrared rays that corresponds to the temperature drop during the normal heating of the end portion (3b) of the semiconductor wafer (3), the central portion of the semiconductor wafer (3) ( The entire 3a) and the end (3b) are heated at a uniform temperature. The infrared rays that heat the end portion (3b) of the semiconductor wafer (3) from the lower surface were originally wasted,
This is effectively used.

The local heating optical means (10) of the lamp annealing apparatus of the third embodiment of FIG. 3 is a reflecting mirror (10c) arranged on the diffusion plate (5). The reflecting mirror (10c) uses the infrared rays of the lamp light source (1) reflected by the reflector (4), which are originally wasted and do not contribute to the heating of the semiconductor wafer (3), to the reflector (4). Reflect towards. The infrared light reflected by the reflecting mirror (10c) is reflected by the reflector (4) and finally applied to the end portion (3b) of the semiconductor wafer (3) to locally heat the end portion (3b).

The apparatus shown in FIG. 3 irradiates infrared rays from the lamp light source (1) onto the entire upper surface of the semiconductor wafer (3) in the same manner as the apparatus shown in FIG. The reflecting mirror (10c) reflects the infrared rays that have been originally wasted after they have come off the wafer (3), and the infrared rays locally heat the end portion (3b) of the semiconductor wafer (3). Therefore, the infrared ray irradiation amount of the end portion (3b) of the semiconductor wafer (3) by the reflecting mirror (10c) can be calculated as follows.
The semiconductor wafer (3) is heated at a uniform temperature when the amount is set to correspond to the temperature decrease during normal heating.

Also in the case of the apparatus shown in FIG. 3, since the reflecting mirror (10c) is in a clean space surrounded by the reflector (4) and the diffuser plate (5), the reflecting mirror (10c) becomes cloudy and the reflectance changes. It is easy to maintain and manage without worrying about it.

The lamp annealing apparatus shown in the fourth embodiment of FIG. 4 has a specific heat storage member (11) near the end (3b) of the semiconductor wafer (3) in the chamber (7) of the apparatus shown in FIG. Is additionally installed. Heat storage member (11)
Is a quartz block or the like having a large heat capacity, which is heated by heat rays from the lamp light source (2) on the outer periphery of the chamber (7).
When the heat storage member (11) is a quartz block, it can be integrated with the quartz stage (8 ').

The semiconductor wafer (3) on the stage (8 ')
And a semiconductor wafer (3) on which a heat storage member (11) is mounted near the end (3b) is placed in a chamber (7) and the inside of the chamber (7) is kept in a predetermined gas atmosphere. (2) is turned on to heat the semiconductor wafer (3) and simultaneously heat the heat storage member (11). Although the temperature of the end portion (3b) of the heated semiconductor wafer (3) tends to decrease due to heat radiation, since the space near the end portion (3b) is kept in a high temperature atmosphere by the heat storage member (11), Part (3b)
Of heat is suppressed, and the temperature decrease of the end portion (3b) is suppressed. As a result, the semiconductor wafer (3) is heated with a uniform temperature distribution throughout.

The quartz block is made of silicon oxide and absorbs infrared rays like the semiconductor wafer (3), and is therefore heated by the arc lamp of the lamp light source (1). Therefore, when the heat storage member (11) of the quartz block is added to the prism (10a) and the reflecting mirror (10b) near the end of the semiconductor wafer (3) in the apparatus shown in FIGS. 1 and 2, respectively, the prism (10a) And the light is condensed by the reflecting mirror (10b), and heat is prevented by the heat storage member (11),
Partial heating of the end (3b) is further promoted. Also, the heat storage member (11), which is similar to silicon as the semiconductor wafer (3), may be selected.

The present invention can be applied not only to the semiconductor wafer (3) but also to heating other objects to be heated one by one.

[0030]

Since the present invention has the above-mentioned structure, it has the following effects.

According to the heating device (lamp annealing device) of the first to third aspects, the temperature of the end portion of the semiconductor wafer, which is uniformly heated by the infrared rays of the lamp light source, tends to decrease due to heat radiation. This end is locally heated by irradiating infrared rays more intensively than the others with the local heating optical means such as a prism or a reflecting mirror, so that the temperature drop at the end of the semiconductor wafer is suppressed and the entire semiconductor wafer is made uniform. It becomes possible to heat with a uniform temperature distribution, and it becomes possible to perform heat treatment such as uniformly pushing impurities into the entire semiconductor wafer, and to make the quality of the semiconductor elements formed on the semiconductor wafer uniform.
It is effective in improving the yield.

Also in the heating device (lamp annealing device) according to the fourth aspect, the heat storage member arranged near the end of the semiconductor wafer suppresses the heat radiation at the end of the semiconductor wafer and facilitates uniform heating of the entire semiconductor wafer. Therefore, it is effective in making the quality of the semiconductor elements formed on the semiconductor wafer uniform and improving the yield.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part showing an outline of a heating device according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a main part showing an outline of a heating device according to a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a main part showing an outline of a heating device according to a third embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of a main part showing an outline of a heating device according to a fourth embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a main part showing an outline of a conventional heating device.

FIG. 6 is a vertical cross-sectional view of an essential part showing an outline of another conventional heating device.

[Explanation of symbols]

 1 lamp light source 2 lamp light source 3 semiconductor wafer 10 optical means for local heating 10a prism 10b reflecting mirror 10c reflecting mirror 11 heat storage member

Claims (4)

[Claims] 1. An apparatus for uniformly irradiating and heating infrared rays from a lamp light source to an entire object to be heated, wherein the infrared rays of the lamp light source are concentrated and applied to the end of the object to be heated more than others. A heating device having a heating optical means. 2. The heating device according to claim 1, wherein the local heating optical means is a prism for refracting infrared rays from the lamp light source and irradiating the infrared rays to the end of the object to be heated. 3. The heating device according to claim 1, wherein the local heating optical means is a reflecting mirror that reflects infrared rays from the lamp light source to the end portion of the object to be heated. 4. An apparatus for uniformly irradiating and heating infrared rays from a lamp light source on a whole body to be heated, the heat storage member having a large heat capacity to be heated by the infrared rays of the lamp light source in the vicinity of an end of the body to be heated. The heating device is characterized in that.