JPS60258928A - Device and method for heating semiconductor wafer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor wafer heating apparatus and method.

The apparatus and method of the present invention play an important role in connection with the manufacturing of various forms of semiconductor wafers.

For example, the apparatus and method of the present invention may include a glass inert layer (gl
Ass passivation 1ayens) is made to flow again and silicide (5ilicid, es
) can be formed. However, the method of the present invention utilized for this application primarily involves annealing the ion-in-blank+4 conductor wafer to remove the stress caused by the ion-implant process and to remove the stress caused by the ion-implant process.
The implant dopants) can be fully activated and in-phase epitaxial growth can be regrown to repair the damaged crystal lattice structure.

(Prior art) Semiconductor materials (e.g. silicon, gallium arsenide, etc.)
Dopant implant processing has traditionally been performed using a machine that uses high voltage to accelerate implant ions toward the semiconductor surface.

The amount of doubant penetration is determined by the magnitude of the accelerating voltage of the doubant ions, and is, for example, 0.2 microns.

The annealing required after ion implant treatment has hitherto been performed in a heated melting furnace. Such furnaces range from 4 inches (10,16 cm) to 17 inches (17 cm), for example.
, 78 centimeters) and a length of, for example, 4 feet (122 meters) to 6 feet (1,83 meters). A heating coil is wrapped around the tube - and the hearth plate passes through the furnace. Each furnace plate accommodates, for example, 30 to 40 wafers. The temperature inside the furnace is adjusted to a desired level, e.g.
The temperature is slowly raised to 0.00°C and then maintained for a certain period of time. Thereafter, a slow cooling period is provided.

The time required for semiconductor wafers to be annealed in such a furnace is typically 30 to 60 minutes.

Traditionally, there has been a strong desire to rapidly anneal large diameter semiconductor wafers (short time annealing). Various documents and many patent specifications have been published regarding rapid annealing, and various attempts have also been made. Rapid annealing operations typically involve heating the wafer to a high temperature for a short period of time and maintaining the wafer at high temperature for about 1 to 2 seconds. By shortening the process as much as possible, implant ions do not diffuse into the bulk semiconductor material and circuit speed is maximized. Please refer to FIG. In the figure, the amount of diffusion caused by certain prior art rapid annealing processes is illustrated by the dotted curve. It can be seen that this curve closely approximates the curve for the case of 6 implants.

It is extremely difficult to perform rapid annealing of large diameter semiconductor wafers reliably and economically. This difficulty is primarily due to the characteristics of the wafer itself. Some of these characteristics will be explained.

The diameter of the wafer is 4 inches (10,160), 5 inches (12,7 m) or 6 inches (15,24 cm).
) Generally, the thickness is about 0.5 mm. Because the thickness is very small compared to the diameter, heat transferred to some areas of the wafer is not quickly transferred to other areas. As described below, heat is not conducted from some regions of the wafer to other regions, and most of the heat radiates away from the wafer.

Due to the size of the wafer and because the average specific heat of silicon is 1.0 joules per duram, fleeting energy is required to heat a silicon wafer to 1000-1200° C. for a few seconds. For a standard 0.5 mm thick wafer, heating to a temperature of 1200° C. requires 145 joules per square centimeter. At a temperature of 1200℃, from the entire surface of the wafer (assuming the emissivity is 07) 18W) /
crl 'i radiation (loss). Thus, for example, a 4 inch (1016 crn) diameter wedge is 1200 crn.
When the temperature is ℃, 2.8 kilowatts of heat is radiated as a whole. To maintain the wafer at 1200°C, one side of the wafer must absorb 36 W/CJ tit continuously, and 187 W/CJ tit if heated on both sides.
TS) / It is necessary to continuously absorb the heat of Ca.

Next, optical properties of semiconductor materials will be explained.

Most semiconductor materials have a very high reflectivity (3.0 to 4.0) in the wavelength range of 0.3 to 40 microns. This means that 30% of the radiation incident on the semiconductor material
This means that 40% of the light is reflected. This reflectance is several times higher than that of glass, for example. Although there is a large amount of reflection, a large amount of heat is radiated from the water even when it is relatively cold. Of the incident radiation in the range of 1.1 to 8 microns, 40 to 50 percent is transmitted through the wafer at temperatures below 500-600°C. Therefore, hot wafers radiate, reflect, and transmit large amounts of heat.

Additionally, wafers have the property that when exposed to intense heat and physical stress, they cannot maintain the necessary flatness and can easily bend. Furthermore, various parts of the wafer may be deformed into waves due to thermal shock.

Another important feature is that relatively long periods of rapid annealing can have adverse effects due to non-uniform heating, i.e. the uneven amount of radiant energy transferred to different parts of the wafer. However, such relatively long "rapid annealing" periods are undesirable; they lengthen the fabrication time, increase the amount of downward diffusion of the dopant, and thus reduce circuit speed.

In response to the problems of rapid annealing, attempts have been made in the prior art to solve these problems. This is explained in detail in two documents. Recent ones include PieterS, Burggraaf (Semic
onductor International, 1
December 1983 issue, pp. 69-74), ``1983 Edition, Current Status of Rapid Wafer Heating Technology.'' In a slightly earlier document, T, 0. Sedgwiclc (Jo
urnalof the Electrochemical
al 5ociety: 5o11d-8tate
5science and technology,
There is a "short-time annealing" according to (February 1983 issue, pp. 484-493). Both of these documents are used herein as examples of citation.

Burggraaf's article emphasizes the importance of uniform heating. The argument (on page 70) is as follows. To make the F wafer temperature uniform,
This is the most important issue that distributors need to consider when designing their manufacturing systems.

Wafer temperature uniformity during rapid wafer heating is important to minimize slip (crystalline dislocation) and wafer distortion that occur at high temperatures.

Additionally, wafer temperature uniformity can be improved by dopant activation treatment (
This affects the uniformity of dopant activation) and junction depth. From a practical point of view, uniform heating is
This is an important issue in creating manufacturing tools for rapid wafer heating. .....To make the temperature uniform, it is necessary to make the radiation area very uniform. In the commentary of the cited literature, the following points are emphasized in relation to the uniformity of junction depth:

Since the wafer is cut into hundreds of elements, it is important that all of these elements are homogeneous. Differences in junction depth due to temperature non-uniformity are one of the disadvantages of adding a rapid annealing step to a viable production line.

In the literature by Mr. Sedgwick cited earlier, imbunt ions are activated and various point defects are detected.
It is shown that in order to remove the at-day), it is necessary to operate at as high a temperature as possible. Applicants' view is that many high-temperature operations use scanning laser beams that, while adequate in terms of temperature, can heat only a few localized areas, causing distortion, slip, waviness, and other defects.

Other key requirements related to a viable rapid-burning process include:
(For example) Bu, rggraaf's literature (70 pages)
There is wafer contamination mentioned in . To prevent this contamination, it is important to rapidly heat the wafer to 800-1100° C. (above breaking point) without contacting and contaminating the wafer. It is therefore clearly undesirable, for example, to use plates preheated to high temperatures. This is because the material of the plate raises the temperature of the wafer to the above temperature range.

The price of the equipment, the cost of operation and maintenance, and the degree of difficulty are very important factors in determining whether rapid annealing equipment can be used in a widespread production line. Efficiency, simplicity, relative compactness, robustness, ease of maintenance, etc. are particularly important for production line operation.

Definitions of terms used in connection with wafer heating There are basically three ways to heat the wafer.

(a) Adiabatic heating (Adiabatic) - Energy is supplied from a pulsed emitting energy source (laser, ion beam, electron beam) over a very short time period of 10-100XIO seconds. This high-density, short-duration energy melts the surface of the semiconductor to a depth of 1 to 2 microns.

(b) Thermal flux heating
x energy is delivered for 5 x 10' to 2 x 10-'' seconds. The thermal flux heating creates a substantial temperature gradient over 2 microns from the surface of the wafer down, but uniformly throughout the thickness of the wafer. It never heats up.

(C) Isothermal heating (5othθrmal) - Energy is applied over a period of 1-100 seconds to raise the temperature substantially uniformly throughout the thickness of the wafer in the desired area of the wafer.

A hypothetical diagram of isothermal heating, heat beam heating, and adiabatic heating is explained in FIG. 6 of the present application. These curves are not drawn to scale. The flat area at the top of the adiabatic heating curve is the melting point of silicon, 14
It is located at 10°C.

This is because latent heat of fusion is required to melt up to 2 microns of the upper layer of the wafer.

SUMMARY OF THE INVENTION The present invention provides a practical, economical, and efficient apparatus and method for rapidly heating semiconductor wafers using thermal radiation in the visible and infrared regions of the spectrum. It is in. Of particular importance is the optical combination of radiation sources (tungsten halogen lamps, xenon arcs, krypton arcs, mercury arcs, electrodeless radio frequency sources, etc.) directed toward the wafer being processed. This optical combination ensures that the radiation density at the target surface on the wafer surface is approximately uniform, resulting in no steep temperature gradients across the wafer.

According to one form of the present invention, a light collecting end is used in combination with a radiation source disposed within the housing, and the radiation source and the semiconductor wafer are arranged in a paired relationship. In a highly preferred embodiment, the collection endpiece consists of a reflective collection power raidoscope containing a radiation source. These combinations provide a fast, efficient, economical, and commercial method for substantially uniformizing the radiation flux at the target surface.

According to another aspect of the invention, an extension of the condensing end is provided on the side of the wafer away from the radiation source and extends through or around the wafer and away from the wafer. The function is that a small amount of the radiant energy is reflected uniformly and returned to the wafer.

In another important embodiment, the same or different radiation sources are provided in the extension of the kaleidoscope.

In either case, a substantially uniform (directly directed and reflected) heat source is provided on both sides of the semiconductor wafer.

A scanning laser is not required, but does not preclude the use of a laser as a radiation source. The heat source here is a large laser combined with a concentrator that evenly distributes the laser beam over the entire wafer surface.

Additionally, a system is described for automatically heating wafers in a controlled environment for annealing or other purposes.

The invention also relates to the combination of uniform isothermal heating and hot wire heating. For example, isothermal heating is performed by a continuous wave (CW) radiation source placed within the optical cavity. By controlling the lamp output, the temperature rise rate is approximately 20° per second.
The temperature is from 0 to about 500°C (or higher).

Once the silicon wafer reaches a predetermined temperature in the range of approximately 800-1100°C, a second radiation source, a high power pulsed emitting lamp, is turned on to increase the surface temperature of the silicon wafer to 1200-1400°C (or higher). ). The surface of the wafer is therefore annealed and freed of defects.

By using the method described in the previous step, without contacting the wet surface) 1
It is possible to quickly heat and heat up the dyeing process.

Rapid heating and uniform optical combination can be achieved by installing multiple halogen lamps and high-power (pulsed emission) lamps in the same condensing optical system cavity, and heating the semiconductor material using a combination of isothermal heating and hot wire heating. obtained by doing. Before applying hot wire heating to raise the surface temperature to 1200-1400°C, the wafer temperature was first raised to 800-140°C.
The combined heating method, which raises the temperature to 0° C., significantly suppresses the development of internal stresses caused by very rapid annealing. Due to the very rapid annealing performed by the method described above, the solid phase is epitaxially regrown with as little diffusion of doubants as possible.

Other important aspects of the invention concern lamp construction, cooling and temperature control.

Prior art, known for the past decade, heats the workpiece by non-uniformly directing light or other radiant heat sources at the entrance of a concentrator trowel. Due to the action of the condenser, the light is made relatively uniform before it reaches the exit end. Some types of such light enclosures employ diffusely reflecting surfaces, either wholly or partially, on the interior surface of the light enclosure.

The second type of condenser used in the prior art described above is called a "kaleidoscope".This second type of condenser can provide a uniform temperature and This is particularly preferred because of its high efficiency.

This condensing rod has a non-diffuse reflective inner wall (at least the main one) having a high reflectance and having a predetermined cross-sectional shape. The shapes of these condensing rods include squares, regular hexagons, regular triangles, and rectangles.

As used herein and in the claims, the term 'kaleidoscope' refers to a reflective collection enclosure adapted to focus a relatively uniform radiation flux onto a target surface. The flat, non-diffuse reflective interior walls of the optical cone cause multiple reflections of the incident radiation energy to cover the target surface with energy. In many instances, the kaleidoscope can be progressively tapered (e.g. According to the invention, the applicant uses a condensing mortar, particularly preferably a kaleidoscope, in a novel way.The novel method comprises: It plays an important role in processing large diameter semiconductor wafers.

According to one form of the invention, the radiation flux is not sent into the condensing housing from the outside, but inside the concentrating housing itself.
Particularly preferably, a scattering radiation source is installed close to one end of the condensing rod. The ends of such focusing trowels are closed and the interior surface is coated to have a high reflectivity. By installing an internal diffuse radiation source, radiation flows in all directions and is reflected towards a target surface located at a distance from the radiation source. The configuration of the invention described above provides a very compact and efficient device capable of maintaining the temperature at a predetermined level at the target surface.

According to another form of the invention, the semiconductor wafer is placed at a desired point along the length of the condensing iron at a considerable distance from the radiation source, and across the target plane, i.e. across the wafer. The radiation flux is made to be almost uniform over the entire surface. For example, significant advantages can be obtained, such as eliminating the artefact effect and achieving high efficiency. In this case, the wafer is not placed at the exit end, but in an almost completely enclosed optical cavity where all walls are reflective. That is, both end walls combine with the side walls of the kaleidoscope to form a completely enclosed optical cavity. This optical system cavity plays an important role in uniformly heating the semiconductor wafer.

The diameter of the condensing end body, that is, the diameter of the elongated optical system cavity, is
The size can be adjusted as required depending on the diameter of the semiconductor wafer. Therefore, for example, 4 inches (10,16 cm)
) diameter is 4.5 inches (11,4 inches).
It can be processed in a kaleidoscope with an internal diameter of 3 crn). On the other hand, the wafer 1 with a diameter of 6 inches (15,24 crn) preferably has a diameter of about 7 inches (17
, 78 cm ) within a kaleidoscope.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

A first embodiment is shown in FIGS. 1-3 and 8. This embodiment is suitable for semiconductor wafers with at least low density implants, i.e. with implant densities up to 5x10 ions/ct&. - The second embodiment described below in connection with FIGS. 4 and 9 is suitable, at least at present, for semiconductor wafers with high density implants, i.e. with an implant density greater than lXl0" ions/d. There is.

Please refer to FIGS. 1 to 3. Kaleidoscope (Ka
lθ1doscope) type light collecting end is reference number 1.
It is indicated by 0. In the illustrated form, this condensing end body consists of four metal walls 11.

These walls 11 (for example made of aluminum) are fixed together to form a square (FIG. 3). The end of the pipe with the radiation source inside, ie the upper end as seen in FIGS. 1 and 2, is closed by a metal end wall 12 (for example made of aluminum). This end wall 12 lies in a plane perpendicular to the longitudinal axis of the collector end.

The inner surfaces of walls 11 and 12 have a high reflectivity for the radiation originating from the radiation source used. A non-diffusive coating 13 of gold is deposited on the surface of the inner wall, at least for the preferred radiation source described in detail below. This coating 13 is deposited on the polished wall surface.

As shown in FIGS. 1 and 2, the radiation source 14 is arranged in an optical cavity 16 formed by walls 11 and 12, and in order to maximize efficiency and miniaturization, is located close to. The preferred radiation source for continuous wave (CW) operation is a row or bank of lamps 17 arranged relatively closely together, covering almost entirely the ends of the cavity 16 and emitting light in all directions. are doing. A preferred radiation source embodiment comprises multiple layers of parallel tubular lamps. The lamps are stacked in rows to maximize light from the upper layer downwards toward the kaleidoscope. A preferred lamp is a quartz halogen lamp. However, other types of CW clamps such as argon, xenon, mercury, etc. can be used. The lamp is arranged in a plane perpendicular to the longitudinal axis of the kaleidoscope.

The semiconductor wafer being processed is designated by the reference numeral 18. This semiconductor wafer is placed in a target plane perpendicular to the longitudinal axis of the kaleidoscope. The illustrated semiconductor wafer is located directly below the lower edge 19 of the kaleidoscope wall 11.

In the illustrated embodiment, the target surface of semiconductor wafer 18 is
The wafer is spaced apart from the end wall 12 by a distance not more than twice the diameter of the wafer. Thus, if the inside dimensions of the kaleidoscope are finches (17.78 cm), the semiconductor wafer 118 may be spaced, for example, 12 inches (30.48 cm) from the wall 12. In this way, the aspect ratio can be set to 2:1.

Even with a relatively small aspect ratio, the light flux applied to the front surface of the semiconductor wafer 18 is uniform within a range of not more than a few percent, for example, within a range of ±2 percent or less.

As mentioned above, a very important and unique feature of the apparatus of the present invention is that it can produce a nearly uniform radiant flux intensity on the wafer surface (while being practical, efficient, and economical). There is a particular thing. These characteristics are obtained by multiple reflections of radiation (in the visible and infrared range) emitted by the rung.

Radiation emanates from the lamp in all directions.

Radiation diverging vertically downward is not reflected and impinges directly on the wafer surface. Other radiation reflects back and forth between walls 10 and impinges on the wafer surface. The remaining radiation reflects from the end wall 12 and reaches the wafer surface either directly or after reflection between one or more walls 11.

Some of the radiation, i.e. radiation that diverges along the plane of the lamp filament, reaches the surface of the lamp filament.
1. n, 1-70・So L-7 radiation tr):, 7!
It serves as a beneficial energy conserver to help heat the 51y.

The semiconductor wafer 18 is held by a ring 21 as shown. Said ring 21 is made of quartz and has a diameter substantially larger than the diameter of the semiconductor wafer. By making the diameter larger than the wafer 71, edge effects, ie, the temperature at the edge of the wafer differing from the temperature at the rest of the wafer 71, are prevented. Further, a handle 22 made of quartz is connected to the ring 21 and passes through to the outside. A curved support element 24 made of quartz is attached to the ring 21 and curves upward from the underside of the wafer 18 to provide point contact support for the wafer. In other words, the end of the element 24, which also extends from the ring 21, is pointed and directed upward, so that the contact surface between the semiconductor wafer and the quartz can be minimized.

Although it is possible to avoid any void area on the underside of the semiconductor wafer 18, an alternative is to place the wafer in the same plane as the lower edge 19 of the side wall 11 of the kaleidoscope and to extend the wafer from that lower edge. The lower wall can also be omitted. In such a configuration, baffles, reflectors, etc. are placed around the wafer relatively close to, but not in contact with, the wafer. Although such structures function quite effectively in certain applications, the structures described below are particularly preferred.

A second condensing piece designated by numeral 29 is attached in axial contact with the first kaleidoscope 10 . Particularly preferably, the condensing iron body 29 has the same cross-sectional size and shape as the kaleidoscope 10, and has the same cross-sectional size and shape as the kaleidoscope 10.
It is a kaleidoscope that is aligned both circumferentially and axially with 0.

The second kaleidoscope 29 is therefore adapted to form a long, integral kaleidoscope together with the first kaleidoscope 10. This kaleidoscope 29 has a semiconductor wafer 18 in the middle area. The kaleidoscope 29 includes a side wall 31 and an end wall 32, each symmetrically corresponding to the side wall 12. However, end wall 32 is closer to semiconductor wafer 18 than end wall 12, and very satisfactory results are obtained. In the embodiment described above, the diameter of the kaleidoscope is a finch (17,
78 cm), and the semiconductor wafer 18 is spaced 12 inches (30.48 cm) from the top end wall 12. The distance from wafer 18 to bottom end wall 32 is (for example) about 7 inches. Therefore, the aspect ratio of the optical system void area below the semiconductor wafer 18 is 1.

The distance from the semiconductor wafer 18 to the lower optical system cavity can be shortened as described above. This is because any reflected light within the optical cavity forms two paths: one toward the end wall 32 and one back from this end wall.

The distance can be further reduced by applying a diffusely reflective coating to the end wall 32.

When the semiconductor wafer 18 is relatively cool, having just been energized by the radiation source 14, most of the radiant energy is transmitted through the wafer as described above. Moreover, much of the energy passes around the edges of the semiconductor wafer, particularly in the corner regions shown in FIG.

As the semiconductor wafer becomes warmer, it becomes a radiant black body and radiates energy downward to the portion of the optical system cavity below the semiconductor wafer 18.

All through semiconductor wafers! Much of the energy passing through the wafer V and radiating from the wafer after it has warmed up is reflected by the coating 33 on the walls 31 and 32. Therefore, after several reflections, the energy travels upward toward the target surface and impinges on the bottom surface of the semiconductor wafer 18 in a substantially uniform manner. The semiconductor wafer 18 is therefore rapidly heated from both sides, although in the illustrated embodiment a single radiation source 14 is used.

The edge effect, that is, the absence of a substantial temperature difference between the edge of a wafer and the center of the wafer,
These are the main features of the invention. Heating is performed substantially uniformly over the entire surface of the wafer.

Furthermore, since the part that actually comes into contact with the wafer is the sharp tip of the support element made of quartz, it is not contaminated. As will be explained below, the conditioned air and, if necessary, the vacuum applied around the wafer prevents oxidation of the wafer and provides other favorable results.

Adjacent to the bottom wall 32 and at the same distance from the semiconductor wafer 18 as the first row 14, a second row of lamps 170 or other radiant heat source 14 can be placed with the same effect. can get. In such a configuration, the semiconductor wafer/−
18 is uniformly irradiated from both sides. In each example, one radiation.

The heat flux emanating from the source bounces between the reflective coatings a sufficient number of times to make the heat flux uniform at the target surface. Additionally, the energy passing through and around the wafer is uniform by the time it bounces off and reflects back to the target surface a sufficient number of times.

Figures 4 and 9 show embodiments using different types of radiant heat sources. One radiant heat source is CW and the other radiant heat source is a pulse or flash heat source. Therefore, the present invention can also be used in manufacturing methods.

In this method, isothermal heating and thermal flux heating are combined as described above and as will be explained in detail below. In FIG. 4, the radiation source 14 is shown in a bottom position instead of the top shown in FIG. The radiation source 14 is shown schematically in longitudinal section in FIG. The arrangement of source 140 lamps at the bottom of FIG. 4 is the same as that of FIGS. 1 and 2 described above.

The upper collecting end is very preferably a kaleidoscope as already mentioned. This upper condensing end is reference number 1
0a, its walls at 11a, the non-diffuse reflective coating at 13a, and the end walls at 12a. The lower condensing end (kaleidoscope) is the same as that described in Example 7 described above, but is oriented in the opposite direction. Therefore, the same reference number 10 etc. will be used.

The radiation source at the top of the kaleidoscope 10a is designated by the reference numeral 46. The radiation source is a pulsed or flash radiation source, and three flash tubes 47 are shown. These flash tubes 47 are arranged parallel to each other and spaced apart in a plane perpendicular to the axis of the kaleidoscope. - By way of example, each of the three flashtubes 47 is an air-cooled linear flashlamp, with a power output of 50 to 100 microseconds (jj) 70
It is designed to dissipate 0 joules of heat. Because of the characteristics of the flash tube, it is preferable to use gold in quartz loge/aw lamps, but in the case of this flash tube a non-diffuse reflective coating of aluminum is used.
a is preferred.

The flash tube 47 may be, for example, a xenon flash tube, which emits high output and instantaneous flash light when strobe light is emitted. Kaleidoscope 10a
Due to internal reflection within the wafer 18, the energy from the pulsed source 46 uniformly heats a large area of the wafer 18. The flash tubes 47 are designed to emit light simultaneously.

In one embodiment (not shown) of the device according to the invention, the flash tube 47 is omitted and the compound eye condenser lens (fl
eye-eye integrating 1ens)
It is attached to the center of the upper wall 12a coaxially with the '1 kaleidoscope 10a. A neodymium YAG laser beam or a neodymium glass laser is placed above the kaleidoscope 10a, and the laser beam is directed to a compound eye condenser lens on the wall 12a. Then, at the same time as the laser pulses are emitted, the semiconductor wafer 1 is
The radiant energy reaches the upper front surface of 8. Such pulse heating operation using a laser is effective because a uniform heating action is applied to the CW source 14 as well.

′! According to the method of @1, a CW radiation source is used in combination with a focusing cone to rapidly and uniformly heat a semiconductor wafer over a period of time to the temperature required to obtain the desired effect. The heating rate can be controlled to desired conditions in a programmed manner. The heating operation is isothermal heating as indicated at the beginning of the specification and shown in FIG. The focusing cone is in a highly preferred form a kaleidoscope as already described.

When attempting to achieve the desired effect of rapidly annealing ion-implanted semiconductor wafers, this method involves supplying a large amount of power to the CW source and then rapidly reducing the power to "hold" the CW source as soon as possible. temperature and then sufficiently reduce or remove the power to cool the semiconductor wafer (power can be reduced in a programmed manner to provide complete control over the cooling process).

The rate of cooling within the optical cavity is much slower than in open space. ) Preferably the rate of temperature rise (for silicon) is 20 per second.
0-500°C. The holding temperature for silicon is preferably 1000-1200°C and is held at this temperature for several seconds. A cooling period of about 10 or 15 seconds follows. A typical time versus temperature relationship is illustrated in FIG. FIG. 8 shows a relatively steep temperature gradient on the left, a flat period at the top of the gradient, and a cooling period on the right. This curve is for silicon. The silicon has approximately 141
It has a melting point of 0°C.

As already indicated, the first manufacturing method described above is based on a lower density doubant implant.
At least at this stage, it is preferable for use in pant implants. Next, a second method, which is currently preferred for high-density implants, will be described.

A second method for rapidly annealing dopant-imposed semiconductor wafers is to uniformly and isothermally heat such wafers to a predetermined temperature well below the wafer's melting point, and then to The method includes continuous beam heating of the upper surface area (adding implant treatment) and then cooling of the wafer. Thermal flux heating (this term is specified at the beginning of this specification) is preferably carried out near the melting point of the semiconductor material;
As shown by the rise in the central region of FIG. 9, temperatures comparable to the 1410 DEG C. melting point of silicon are never reached.

More specifically, the second manufacturing method includes the step of isothermally heating the Sydopant implant semiconductor wire using a CW radiation source. The aW radiation source is preferably an array of quartz halogen lamps arranged in an optical cavity formed by a collection cone (preferably a kaleidoscope). The power supplied by the CW clamp is 20 per second.
It is controlled to obtain a temperature rise rate of 0-500°C (or more). Silicon wafer is 800-
Once the programmed temperature of 1100°C is reached, high power is then applied to the bank of pulsed lamps to rapidly increase the temperature of the dopant implant surface of the wafer to 1200-1400°C. Therefore, annealing the surface area of the wafer,
Defects can be removed.

The combined heating method allows rapid and efficient heating without contacting and contaminating semiconductor wafers.
Furthermore, semiconductor wafers can be heated effectively.
For example, there is no need to use a preheating plate. By installing a dual quartz halogen lamp and a dual high power (pulsed emission) lamp in the same cavity, the semiconductor material can be heated isothermally by both lamps.

The pulse emission time of the pulse lamp train can be from 5 microseconds to 1000 microseconds.

The thermal flux energy absorbed at the dopant implant surface of the semiconductor material is fc 0 per 5 microsecond pulse.
．． It can range from 5 J/ct& to IOJ/cJ per 1000 microsecond pulse.

What I would like to emphasize is that in the second manufacturing method described above and shown in Figure 9, this isothermal heating can be done at a lower temperature than when the isothermal heating (without pulses) is used as shown in Figure 8. Therefore, it is preferable. Since the surface temperature of the semiconductor material can be rapidly raised to near the melting point, the annealing rate can be increased (considerably faster than the annealing rate when the relationship between temperature and annealing rate is linear). As a result, lower isothermal heating temperatures can be utilized.

For example, using isothermal heating to reduce the temperature of the entire wafer to approximately 1
The temperature can be uniformly raised to 100℃. After a few seconds, the pulse source is energized to form a rise (FIG. 9), raising only the upper surface area of the wafer to peak temperature.

However, the temperature does not rise to the melting temperature of the particular semiconductor material (silicon in the example shown in FIG. 9). The pulses are short enough to heat and anneal an area at least as deep as the dopant implant layer. The duration of the pulse is short enough to minimize slippage of the silicon panel (particularly after isothermal heating) and also to cause little heating of the entire conductor of the wafer. Since the entire wafer is not heated, the temperature of the entire wafer is 1100°C as explained in the previous example.
It's only a few degrees higher than that. This is because the pulse that performs heat flux heating is short.

It is important to emphasize that for other semiconductor materials such as gallium arsenide, the temperature and /''1. A major problem remains. With gallium arsenide, the second method described above can be used to isothermally heat the wafer to a relatively low temperature without evaporation. Then, a pulsed lamp train is used. In more detail, gallium arsenide semiconductor wafers are produced using the second manufacturing method, and the wafers are heated to about 5
00-6001: rapidly annealed by isothermal heating to a temperature in the range of about 950-1000°C.
Increase the temperature to .

The heating operation, which combines isothermal heating and thermal flux heating, is carried out in such a way that melting occurs, that is, the rising temperature shown in Figure 9 rises above 1410°C (in the case of silicon), and then flattens due to the latent heat during melting. It can be done as follows. However, if the step to be performed is annealing, melting is not preferred.

The kaleidoscopes and other devices previously described herein can also be used in combination with pulsed sources in the absence of CW lamps or isothermal heating elements. A pulsed (flash) source of radiant energy is capable of providing either flux heating or adiabatic heating, as illustrated in FIG. To speed up production, means can be used to speed up the cooling of the wafer. For example, during the cooling period, the condensing rod can be segmented and/or the gas flux can be increased.

DESCRIPTION The upper portions of FIGS. 1 and 2 and the lower portion of FIG. 4 illustrate the number and type of lamps 17 that may be convenient for use in a particular device. In this example, the semiconductor wafer 18 has a diameter of 6 inches (15.24 cm), and the inside diameter of the optical cavity is approximately a finch (17.78 cm) inside diameter. Twenty-seven lamps 17 are used, each lamp 17 having a rated power consumption of 1.5 kilowatts. Therefore, the total rated power consumption of the lamps 17 is i per lamp row.
It is 40.5 kilowatts.

Next, a device will be described which provides power to the lamps 17 and cools them effectively so that the optical cavity 16 does not heat up during long periods of use during manufacturing.

As shown in FIGS. 1 and 2, each lamp 17 (preferably a quartz halogen lamp) is substantially longer than the outline of the optical cavity. For this reason, the terminals 48 at the outer ends of the lamps are spaced apart from the walls of such optical cavities. Terminal 48 is connected to mother @49-52. These generatrices are also spaced apart from the walls of the optical cavity. Three of the busbars, referenced 49-51, are located on one side of the optical cavity, each of which connects the terminals 48, K1f of the nine lamps 17.
f1g, tl,? -・#11F, #r* 52 T i
f3! The Q (DfJ) line is located on the opposite side of the optical cavity and is connected to all 27 lamps.

The power supply 53 shown in FIG. 2 is connected to three busbars 49-51 in a triangular or Y-shaped relationship and also to the remaining busbar 52. Such lamps are therefore supplied with three-phase power. The power supply source 53 is preferably of the SOR type, and is preferably of the type that adjusts the power supplied to the lamp with a variable voltage. (One such power source is Westinghouse's Vectrol DiViEliOn).
) is sold from. ) The control signal is the computer 5
4 (FIG. 2) to a power supply 53. The computer 54 is also connected to an optical pyrometer 56. Optical pyrometer 56 is directed through angled aperture 57 and sidewall 11 to the central area of semiconductor wafer 18 .

53-55, the temperature of the wafer is quickly raised (optional or in a pro-dalamized manner) to the desired temperature level by CW heating, as previously described in connection with FIGS. 8 and 9. It is now possible to raise it. It is then possible to maintain the required temperature for a desired period of time and then turn off power to the lamp (optionally - in a programmed manner).

Next, cooling of the CW lamp will be explained. It should be pointed out that the lamp filament is contained within the optical cavity. Thus, for example, each lamp 17 has a filament approximately 6.2 inches (15.75 centimeters) long and is disposed entirely within the optical cavity 16.

At terminal 48, much heat is generated from the lamp. These terminals 48 are spaced outwardly from the walls of the optical cavity, as previously mentioned. With the cooling device of the present invention and the method using the same, the terminals 48 and the bus bars 49-52 can be sufficiently cooled by causing air to flow on both sides of the bus bar. The cooling device and method also allow sufficient cooling of the portion of the lamp 17 within the optical cavity 16 to prevent overheating of the device.

At the same time, the lamp tube will not be cooled too much, causing halogen vapor to deposit on the lamp tube and reducing lamp efficiency.

A cooling housing 59 is provided about the end of the optical cavity in spaced relationship from the optical cavity and the generatrix 49-52. Air or other suitable refrigerant is supplied to housing 59 through conduit 60 and exhausted from the housing through conduit 61. Suitable baffle means, such as vertical baffles 62, connect cooling housing 49 to inlet chamber 63.
and an exit chamber 64. Refrigerant can only flow between these chambers along two predetermined paths.

The first path is a large cross-section path, which passes through the end wall 12 of the optical cavity. The second path leads into the interior of the end of the optical cavity 16 through a larger passageway 66 . The passage 66 is provided for each lamp 17.

Passage 66 is preferably cylindrical and coaxial with the lamp. Therefore, the wall of the lamp does not touch the optical cavity 11. The lamps are not supported by the walls of the optical cavity, but by generatrix 49-52. The busbar is connected to an insulating bracket 67 connected to the wall of the optical system cavity.
It is supported by

Air flowing from the inlet chamber 63 thus enters the upper end of the optical cavity 16 along and around each lamp 17. The air then flows through the top 7 of the optical cavity and exits into the chamber 64 and into the conduit 6.
It flows out through one tube.

The end of the optical system cavity is separated from the cavity portion in contact with the semiconductor wafer 18 by a quartz window 68 (68a in FIG. 4). Therefore, the air does not reach the semiconductor wafer 18, and the strained tempered air can be supplied to both sides of the semiconductor wafer 18, as will be described later.

The combination of cooling means, bus bar and terminal means, and window 68 provides effective and efficient cooling. Therefore, the walls 11 and 12 do not overheat and the bottom area of the cooling housing 59 is provided closer to the semiconductor wafer 18 than the window 68. Therefore, conduction of heat through the end wall 11 of the optical system cavity does not heat the cavity region adjacent to the semiconductor wafer 18. Due to the reflective properties of the inner surface of the kaleidoscope, the semiconductor wafer, e.g.
Even when heated to 0°C, the outer surface of the device 10 is approximately 150°C below (
65.6° C.).

The cooling means for the flash lamp 47 shown in the upper part of FIG. 4 is almost the same as the cooling means for the CW lamp 17. Therefore, it will not be described in detail. Also, flash lamp 47
The power supply for the power supply can be of various configurations well known in the art. Therefore, the explanation is omitted here.

The apparatus shown externally in FIG. 5 corresponds to the embodiments of FIGS. 4 and 9. However, this device can also be used in the embodiments of FIGS. 1-3 and 8. In the latter example, the flash lamp and associated cooling means are omitted.

The upper force raidoscope, designated by reference numeral 10a (FIGS. 4 and 5), is held stationary by suitable support means 70 connected to the housing. The housing is indicated by phantom lines 71 in FIG.

Cooling air for the flash lamp and kaleidoscope 10a is supplied through conduits 72 and 73 connected to the housing 71.
(Figure 5).

The lower kaleidoscope 10 (FIGS. 4 and 5) is not held stationary, but is moved up and down between the illustrated closed position and the open (downwardly lowered) position. With the lower kaleidoscope in said open position, the quartz ring 21 carrying the semiconductor wafer 18 can be rotated in a horizontal plane to move in and out of the optical system cavity. Fifth
Referring to the figure, a fluid actuated cylinder 74 is used to raise and lower the kaleidoscope 10 and its attached cooling device.
and a guide 75 attached thereto. The conduits 60 and 61 leading to the cooling device and projecting outwardly from the flexible housing 71 are made of a suitable flexible material and are capable of deformation in the vertical direction described above.

Three support rings 21 are mounted on a rotary support device 77 driven by an actuator 78 and mounted in a horizontal plane. Two loading cassettes 79 are provided in one station within the housing 71 and two removal cassettes 80 are provided in another station within the housing 71. Although not shown, a suitable pick-up mechanism and a mounting mechanism are provided to accommodate the semiconductor wafer 18 in the mounting cassette and removal cassettes 79 and 80, respectively.
It is designed to send in and take out. 2
By placing one cassette 79 and two cassettes 80 next to each other, continuous mass production can be performed. The cassette is introduced into and removed from the housing 71 through six airlocks. The desired air is filled into the housing 71 and thus into the optical cavity. ,
It can also be nitrogen, helium, etc. Gas flows through conduit 8
2 from a suitable source 81.

It is also possible to connect the gas supply 81 directly to the optical cavity via conduits 83 and 84 shown in FIGS. 2-4. The flow of gas through such conduits has the effect of increasing the rate of cooling.

Therefore, continuous production line operation begins by sending a signal to actuator 74 to
is lowered and then signals actuator 78 to rotate device 77 120 revolutions. As a result, unprocessed wafers 18 are fed into the space between the upper and lower kaleidoscopes. Next, a signal is sent to the actuator 74 to lift up the kaleidoscope 10, and the upper and lower kaleidoscopes 10a and 10 are
The opposing edges of the wafer 18 are brought together to form a closed optical cavity in which the wafer 18 is placed as shown in FIG.

Radiant heat sources 17 and 46 are then operated as described above to anneal 41. wafer 18 by isothermal heating and thermal flux heating. 'L Let's go. Then actui, -7□4t
,, operation □ i T red 1.7, i □.

is lowered and signals actuator 78 to rotate device 77. The processed wafers 18 are then sent to a removal station adjacent to the removal cassette 80 and removed by a pick-up machine, not shown. The wafer is not removed from the optical cavity until it has cooled sufficiently to prevent damage.

The quartz handle 22 of the support ring 21 (groove 23 in FIG.
), passing through a groove in the upper edge of the wall 11 of the lower kaleidoscope 10 (FIG. 4). This handle is connected to one of the arms of the device 77.

It is emphasized that the area around the wafer 18 divided by the quartz windows 68 and 68a forms the ends of the kaleidoscope. When heating occurs, the inert atmosphere around the wafer 18 moves very little. This situation is desirable because substantially all of the radiated heat is not lost by conduction or convection, resulting in a maximally uniform temperature across wafers of various diameters. On the other hand, as already mentioned, the cooling rate can also be increased by flowing an inert gas during the cooling period. Preferably, a cooling means such as the housing 59 is also provided around the second kaleidoscope 29 (lower part in FIGS. 1 and 2).

Although the foregoing detailed description can be better understood from the illustrative examples, the spirit and scope of the invention are not limited thereto.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the combined force raid scope with a portion of the wall removed. FIG. 2 is a longitudinal sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a cross-sectional view taken along line 3--3 in FIG. FIG. 4 is a longitudinal cross-sectional view showing a second embodiment of the device of the invention, taken in a section perpendicular to FIG. 2 (which shows the embodiment of FIG. 1). Accordingly, the lamp in FIG. 4 is shown in cross section and not in side view. FIG. 5 is an outline diagram of an automated system for rapidly heating semiconductor wafers in a production line. FIG. 6 is a graph showing the relationship between temperature and processing depth in isothermal heating, heat beam heating, and adiabatic heating. FIG. 7 is a graph showing typical implant densities at various depths, both when implanted and after different types of hardening. FIG. 8 is a graph showing the relationship between temperature and time in the first example. FIG. 9 corresponds to FIG. 8, but shows the relationship between temperature and time in a second embodiment of the invention. 10... Concentrating iron body 10a... Upper condensing end body 11,
lla...Side wall 12, 12a...End wall 13.13
a... Coating 14... Radiation source 16... Optical system cavity 17... Lamp 18... Semiconductor wafer 19... Lower part mixing 21... Ring 22... Handle 24... - Curved support element 29... No. 2 condensing iron body 31...
Side wall 32... End wall 33... Coating 46.
...Radiation source 47...Flash tube 48...
Terminal 49-52...Bus bar 53...Power supply source 5
6... Optical pyrometer 57... Inclined opening 59 River cooling housing 60.61... Guide t62... Baffle 63.
... Entrance room 64... Exit room 68... Quartz window (5 people outside) - - Nu, 227 microns - 1ff/1 FIG, 8 FIG, 9 Tsuba (excerpt) TffJVt (seconds)

Claims (1)

[Scope of Claims] (1) A hollow light condensing body; a closed end of one end of the light condensing body; and a wall means whose inner surface is a reflective surface, and disposed within the light condensing body. lamp means emitting thermal radiation thereabout and transmitting thermal radiation in both directions along said condensing end body; support means for supporting a workpiece at a support means, said support means being disposed on a side of said ramp means remote from said wall means, said support means supporting a workpiece supported by said support means; is sufficiently spaced from said lamp means to be relatively uniformly heated by thermal radiation emitted from said lamp means, reflected by the inner surface of said wall means, and focused by said optical enclosure. Wafer heating equipment. (2. The heating device according to claim 1, wherein the light condensing device is a kaleidoscope. (3) Heating for rapidly annealing a dopant implanted semiconductor wafer having a large diameter. 1, using a lamp means and a light concentrator to relatively uniformly isothermally heat the wafer; (4) A method for annealing a large diameter semiconductor wafer, the method comprising the steps of heating a semiconductor material and then relatively uniformly heating a dopant implant surface area of the wafer with a thermal flux. , providing a kaleidoscope having a closed, internally reflective end and housing a radiant thermal energy source relatively proximate to the end; and using the kaleidoscope to radiate thermal radiation from the energy source. placing a large diameter semiconductor wafer at a location where the energy is relatively uniform; and heating the wafer substantially uniformly using the uniform energy to achieve the desired temperature. a method for heating a semiconductor wafer, the method comprising: annealing the semiconductor wafer;