JPS6060712A - Infrared ray heating method - Google Patents

Abstract

PURPOSE:To enable to perform an annealing process on both sides of the material to be heated simultaneously by heating both sides of the material to be heated at different temperatures by a method wherein a device for adjustment of supplied electric energy is provided independently on the infrared ray heating lamps which are opposingly arranged on the front and back sides of the material to be heated. CONSTITUTION:The programed power sent from a common power source 9 is supplied to power controllers 13a and 13b through power ratio setting devices 14a and 14b, and each lamp 6 of infrared ray lamp groups 8a and 8b is lighted up using the power set for each lamp group by the setting devices 14a and 14b. The setting devices 14a and 14b output the power W1 of W0Xx% (x=0-100) and the power W2 of W0Xy% (y=0-100) by independently and selectively setting the inputted common power W0 within the range of 0-100%. The power ratio set values (x) and (y) are determined by manual operation performed from outside. As a result, workability is improved due to reduction in annealing manhours, and the improvement in quality can also be contrived by performing an annealing simultaneously on the front and back sides of the material to be heated.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to an infrared heating method which is particularly useful in wafer annealing processes in semiconductor device manufacturing.

In addition to annealing after ion implantation and polysilicon layer formation, the purposes of the conventional heat treatment process for semiconductor wafers include lowering the resistance of the polysilicon layer, recrystallization, and applying aluminum to both the front and back surfaces of the semiconductor wafer. There are also sintering and alloying of metals such as nickel and chromium, and in these cases, an electric furnace is generally used as a heating means. However, with the recent trend toward higher density and higher precision due to VLSI devices in semiconductor technology, electric furnace annealing has begun to reach its limits in terms of electrical activation of impurities in high concentration impurity regions within semiconductor wafers. The development of new annealing technology in line with progress is awaited.

New annealing techniques such as laser annealing, electron beam annealing, and infrared annealing have been reported in the literature, and among them, they are effective and practical for uniformly heating flat, wide-area objects such as semiconductor wafers. An infrared annealing method using an infrared lamp is currently in the process. An example of an apparatus for annealing semiconductor wafers using this infrared annealing method will be described with reference to FIGS. F to 3.

In Figures 1 and 2, (1) is a semiconductor wafer to be heated, (2) is an annealing heating furnace, and (3) (3) is a heating furnace (2) supporting the semiconductor wafer (1). (4a) (4b)
) is an infrared heating device disposed oppositely at two locations, upper and lower, in a heating furnace (2), and a semiconductor wafer (1) is positioned and carried between the two, and annealing processing is performed on both the front and back surfaces. The upper infrared heating device (4a) consists of one gutter-shaped reflector (5) with a parabolic cross section and one linear infrared lamp (6) installed at the focal point of this reflector (5).
It has a structure in which a plurality of sets, for example four sets, of heating elements (7) are fixedly arranged in parallel and fixed to the upper part of the heating furnace (2) with each infrared lamp (6) (6) facing downward. The lower infrared heating device (4b) is a heating element (7) with the same structure as above.
For example, five sets of infrared lamps (6), (6), and - arranged in parallel are fixed at the bottom of the heating furnace (2) with the infrared lamps (6), (6), and - facing upward, and the lower infrared lamp group (8b) and The upper infrared lamp group (8a) is a semiconductor wafer (1)
They are placed at different positions from each other in order to heat them more evenly.

Annealing of the semiconductor wafer (1) targets both its front surface m and back surface n, and although the annealing temperature (thermal reaction temperature) for both surfaces may be the same, it is usually performed at different temperatures because the conditions of both surfaces are different. be exposed. The semiconductor wafer (1) carried into the heating furnace (2) is annealed by heating the surface layer to a high temperature in a short period of about 10 seconds using infrared radiation on both the front and back surfaces. Lamp group (
The lighting of each of the infrared lamps (6) (6), (8b), and (8a) and (8b) is performed by the circuit shown in FIG. That is,
In Fig. 3, (9) is a common power source, (10) is a common power source (9), and programmer 1 (11) is a programmer (11) that determines the amount of power supplied from the common power source (9) to each infrared lamp group (8a) (8b). 10), the power set here is commonly supplied to each infrared lamp (6) (6) of each infrared lamp group (8a) (8b). )- are turned on at the same time with the same power to simultaneously heat both the front and back sides of the semiconductor wafer (1). Furthermore, (1
2a) (12b) is each infrared lamp group (8a)
Thyristor (13a) which is the input gate of (8b)
(13b) is each infrared lamp group (8a) (8b)
This is a power controller that controls and holds the power supplied to the lamp constant using the current I and voltage (2) fed back from the lamp circuit as parameters.

Problems to be Solved by the Invention Incidentally, there is no problem when the annealing process using the circuit shown in FIG. 3 is performed by heating both the front and back sides of the semiconductor wafer (1) to the same temperature. If there is a difference in annealing temperature due to differences in material, skin condition, etc. from the back side n, it is not possible to anneal both sides m and n at the same time. Therefore, if there is a difference in the annealing temperature for both sides m and n, first heat at a higher annealing temperature to anneal one side, then heat at a lower annealing temperature and anneal the remaining side. They are taking turns. Therefore, two steps are required to anneal both the front and back sides of one semiconductor wafer (1), resulting in poor workability.Also, since both the front and back sides are heated twice, the reliability of the process is low, making the infrared annealing method difficult to implement. This made it difficult to apply.

20 Means for Solving the Problems In view of the above-mentioned problems, the present invention provides a means for solving the problems by independently providing heating infrared lamps arranged oppositely on both the front and back sides of an object to be heated such as a semiconductor wafer. 0-100
The present invention is characterized in that a means for adjusting the amount of supplied power is set within a range of %. Therefore, by the above means, it is possible to simultaneously heat both sides of the object to be heated at different temperatures to anneal both sides simultaneously, and it is also possible to anneal only one side.

E. Embodiment When the present invention is applied to the annealing apparatus shown in FIGS. 1 to 3, the upper and lower infrared lamp groups (8a) and (8b) are lit by a circuit as shown in FIG. 4.

The same reference numerals in FIG. 4 as in FIG. 3 indicate the same contents, and the details will be omitted. The difference is that programmed power from a common power source (9) is transferred to two power ratio setters (14).
a) through (14b) the power controller (13
a) (13b) and each infrared lamp group (8a
) The infrared lamps (6), (6), and (8b) are turned on with the power set by the power ratio setting device (14a) (14b) for each group.

Each power ratio setter (14a) (14b) independently selects and sets the input common power WO in the range of 0 to 100%, and outputs a power W of WOXx% (X-0 to 100).
output power W2 of 1, WOXY% (y=0 to 100). This power ratio setting value X, 7 is determined by manual external operation. For example, if the annealing temperature of the front surface m and the back surface n of the semiconductor wafer (1) is the same, then x=y and each infrared lamp group (8a) (8b
) are simultaneously turned on with the same power to perform simultaneous annealing, and if there is a difference in the annealing temperature between the front surface m and the back surface n, the temperature is increased by X% y (x≠y).

Simultaneous annealing is performed by setting (X≠0, y≠0) and simultaneously heating the front and back surfaces m and n to their respective annealing temperatures. In this way, simultaneous annealing of both the front and back surfaces m and n is possible because
This is because almost all of the short-term heating of the front and back surfaces m and n by infrared radiation is concentrated in the surface layer portion. In addition, when annealing only one of the front and back surfaces m and n, it is done by setting X or y on the unannealed side to 0%, or preheating X or y on one side on the unannealed side. Set it to .

Note that the embodiments of the present invention are not limited to the above-mentioned examples, and the layout of the infrared lamps may be appropriately modified depending on the object to be heated.

2. Effects of the Invention According to the present invention, it is possible to easily anneal both the front and back surfaces of a flat plate-shaped object to be heated at the appropriate annealing temperature at the same time. Simultaneous processing on both sides improves quality, making the practical application of infrared annealing effective. Further, in addition to simultaneous annealing of both the front and back sides of the object to be heated, annealing of only one side can be easily performed by preheating the other side, making it possible to perform infrared annealing with great versatility.

[Brief explanation of drawings]

1 to 3 are for explaining the basic technology of the present invention, FIG. 1 is a schematic sectional view of an infrared annealing device, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a block diagram of the heating circuit of FIG. 1, and FIG. 4 is a block diagram of the heating circuit of an infrared annealing apparatus showing a specific example of the apparatus of the present invention. (1)...Object to be heated, (6)...Infrared lamp, (9)
--Common power supply, (14a) (14b) . . . supply power amount adjustment means.

Claims (1)

[Claims] (1) A pair of upper and lower or left and right heating infrared lamps placed opposite each other in the vicinity of both sides of a flat plate-shaped object to be heated is provided with power supply adjustment means independently, so that both sides of the object to be heated can be heated simultaneously or one side can be selected. An infrared heating method characterized by heating.