JPS59171117A - Annealing of semiconductor substrate - Google Patents

Abstract

PURPOSE:To improve the dispersion of the annealing temperature due to the difference of the rise starting temperature and obtain the annealing method with good reproducibility by a method wherein, when a semiconductor substrate is subjected to heat-treatment at high temperature and for a short time by radiation of infra-red rays, a process, by which the rise starting temperature is fixed to a certain value, is added before the heat-treatment. CONSTITUTION:A temperature cycle profile is shown in the figure in which an abseissa represents time (sec) and an ordinate represents temperature ( deg.C). In this profile, 11-12 corresponds to the temperature rising process for pre-heating, 12-13 corresponds to the newly added pre-heating process, 13-14 corresponds to the temperature rising process for annealing and 14-15 corresponds to the short time annealing process. With this procedure, the rise starting temperature for annealing is fixed to the pre-heat temperature A regardless to the initial temperature at the point 11 by adding the new pre-heating process expressed by 12-13. With this constitution, dispersion of the sheet resistance values for every annealing process can be reduced within + or -3% and at the same time residual gas such as O2 contained in the atmosphere can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for annealing a semiconductor substrate, in detail (1. A method for annealing a semiconductor substrate that enables high-temperature, short-time annealing by infrared irradiation with good controllability and reproducibility. It is.

In recent years, the development of highly integrated and high-performance integrated circuits on silicon substrates and gallium arsenide (hereinafter referred to as GaAs) substrates has been progressing using ion implantation technology. These integrated circuits are formed on a semiconductor substrate 2'L f, = p
It is manufactured by integrating basic elements such as cloth, field effect transistors, diodes, etc. on a conductive layer of type or p-type, but in order to further improve the performance of the integrated circuit, It is essential to form a carefully controlled impurity acidity distribution.

Recently, as an annealing method after ion implantation, a high temperature annealing method using infrared irradiation from a halogen lamp or the like111) has been studied. When this annealing method is used, it is possible to suppress the thermal diffusion of impurities in the semiconductor to a smaller extent than the conventional electric furnace annealing method, and it is possible to form a steep impurity concentration distribution.

However, this infrared short-time annealing method (in this case, requires a rapid temperature increase step of up to 100°C/see and control of the annealing time to a positive 17+ m in seconds, so the predetermined temperature cycle There is a problem in that it is difficult to control with good reproducibility. Figure 1 shows an example of a temperature cycle for short-time infrared annealing. In Figure 1, the vertical axis is temperature and the horizontal axis is time. 1, where A is the temperature at the start of heating, B is the maximum temperature reached, and J) IJ is the annealing temperature. There are two main methods for realizing the temperature cycle shown in FIG. 1: H≧ is heat source 1
The applied power (or simply current) is constant ζ, fMj
One method is to control the annealing temperature B by controlling IHI during infrared irradiation, and the other method is to directly measure the temperature of the semiconductor substrate with a pair of thermal lightnings and control the output with a temperature controller. The former method has the plus point of simple device configuration, but on the other hand, it is less susceptible to external disturbances during annealing (
For example, fluctuations in current value due to lamp deterioration! , fluctuations in ambient gas flow rate, etc.), the reproducibility of each annealing remains a problem because it does not have a function to correct the influence of disturbance by itself.

Furthermore, since the annealing salt 1fB is 10 times tangent to the heating start temperature 赵-A, in order to accurately control the annealing salt jWB, it is necessary to make the heating start temperature A the same for each annealing. On the other hand, in the latter method, since the temperature of the semiconductor substrate is raised while feeding back the temperature of the semiconductor substrate, it has a correction function for disturbances during annealing.
Corresponding to the degree A, an over-neat state occurs in the annealing salt 11iB, which is a cause of preventing reproducible annealing at 414'.

The purpose of the present invention is to provide the above-mentioned Ge F temperature onset temperature pF, (17)
The annealing temperature based on JI improves the
An object of the present invention is to provide a high temperature, short time annealing method for a semiconductor substrate with good controllability and reproducibility.

A feature of the present invention is that in the step of annealing a semiconductor substrate at a high temperature and for a short time by irradiating light from a halogen lamp, there is provided a step of fixing the high-temperature annealing temperature at a constant value. It is in.

The contents of the present invention will be explained below along with experimental facts using two examples.

Figure 2 shows the maximum temperature reached on the surface of a semiconductor substrate (ftj) by applying a constant current to an infrared irradiation device (halogen lamp light with a wavelength of 0.4 to 50 μn) and cutting off the current supply after a certain period of time. This figure shows the relationship between the substrate temperature at the start of heating. From Figure 2, it can be seen that by increasing the temperature starting temperature by 1°C,
It can be seen that the annealing temperature increases by 05° C. despite the same temperature raising process.

Therefore, for example, the first annealing is performed at a room temperature of 20°C, and the second annealing is performed at a heating start temperature of 100°C due to the influence of the previous pre-03. If A==, then a difference in temperature of about 40° C. will occur between the two annealing. From the above, in order to improve the reproducibility of the annealing temperature of annealing jji-, it is necessary to keep it constant from the start of temperature rise j#i to every 8xf annealing. The present invention is based on the above experiment-1 results and considerations, and is characterized in that it includes a step of making the y4/i crystal initiation temperature constant (('').

FIG. 3 is a temperature cycle diagram showing an embodiment of the G Itsuki invention. In FIG. 3, the horizontal axis shows time, and the vertical axis shows time r. The feature of this example is that it includes a preheating step of +2-I (+2-I), and by this step, the temperature increase start surface IW of annealing is set to point 11 (where the toughness stage temperature 1 is -irrespective of -1).
(Fixed at 4fi heating temperature A.

Pre-order Illt dust and its duration (4,
The characteristics of the semiconductor substrate (as long as they do not change) can be set to arbitrary values.
50keV(,:SoliniJinio7 f 5
+113 an 'l main input G a As board 9
As a result of applying one corner to 50 °C for a short time of 2 seconds,
The flaking in the sheet resistance region of 77% annealing is ±8Φ in the conventional preheating method including one culm.
On the other hand, it has been confirmed in practice that the upper 3% of the package is lowered to lower humidity. In addition to the effect of reducing oxygen concentration in the annealing atmosphere (containing stone), there is also an effect of removing the residual gas of oxygen in the annealing atmosphere.
Piece! 6. Verify the normal operation of the equipment and power supply system.
There is also another effect that the high temperature annealing temperature can be somewhat relieved. .

The gist of the present invention (point 30 in Figure 3) "r-
f (:'H, eye bar 1 initial temperature f '\i, a constant value ζ is fixed 1-ru (- Well, ; it will go down to Figure 83 (+
fii heating step 12-13+, 1.11↓4n1 (slanted preheating as shown ≦, Menige t: 22-2:3
You can also do fortune-telling.

By using the annealing method according to the present invention, the reproducibility of annealing 71i is improved. It becomes possible to try fortune-telling.

The heat source for heating used in the present invention includes halogen and
It goes without saying that other heat sources such as graphite heaters can be used in addition to lamps, and the heat treatment method of the present invention includes only one heat treatment to obtain ohmic contact other than annealing the ion-implanted layer. The present invention can also be applied to other heat treatments such as heat treatment for forming a metal silicide layer, heat treatment for forming an insulating film using the 0VI) method, and the like.

[Brief explanation of the drawing]

Figure 1 shows the temperature of conventional infrared short-time annealing. Figure 2 shows the temperature of conventional infrared short-time annealing. FIG. 3 is a one-temperature cycle diagram showing one embodiment of the present invention, and FIG. 4 is a 17-temperature cycle diagram showing another embodiment of the present invention. In the figure, +1-12 is a temperature raising process for light heating, +2-13 is a preliminary 7 Jl heat treatment culm, 13-14 is a temperature raising process for annealing, 1.4-15 is a temperature raising process other than short-time annealing, 29
-2: (temperature) Preheating step with ty gradient
It shows 4-0 Ning 11 Figure Cow 8 Do Episode 1 c-sai'7)→ Note 2 {7 0 100 200 300 No 1
1 'I-PA 4'6 5151 degrees (°Q) → darkness (t7) -> vL/-1 figure

Claims (1)

[Claims] 1. A method of annealing a semiconductor substrate, the step of heat-treating a semiconductor substrate at a high temperature and for a short time by irradiation with infrared rays, prior to the heat treatment step, a step of fixing a heating start temperature to a constant value.