JP3911071B2 - High speed lamp heat treatment apparatus and high speed lamp heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-speed lamp heat treatment apparatus and a high-speed lamp heat treatment method used in a high-speed heat treatment process or a thin film production process in a semiconductor IC production process or a liquid crystal panel production process.
[0002]
[Prior art]
Since the conventional high-speed lamp heat treatment apparatus uses a linear lamp, it is particularly difficult to control a circular object to be heated to a uniform temperature distribution. A silicon wafer (hereinafter referred to as a wafer) used for manufacturing a semiconductor IC is circular, and when heated, its temperature distribution becomes concentric. It is difficult to control the temperature distribution when a circular wafer is uniformly heated with a linear lamp. Therefore, in a commercially available apparatus, a method is generally employed in which linear lamps are arranged above and below the wafer so as to be orthogonal to each other and heated. ('94 latest semiconductor process technology / published by Press Journal / p264) In such a conventional method, the temperature controllable range is still rectangular, and it is difficult to make the temperature distribution of concentric wafers uniform. It was. This is mainly because the heat dissipation distribution of the wafer is also concentric, and it is theoretically difficult to control the concentric heat distribution with a linear lamp such as a conventional high-speed lamp heat treatment apparatus.
[0003]
In particular, in order to make the temperature distribution in the wafer uniform during the temperature rise due to high-speed heating (several tens of degrees / second or more), the system must be able to easily control the concentric temperature distribution optimally. However, there is a limit in using a conventional linear lamp. In addition, there is a device that heats up a large number of mini-bulb lamps, but the number of lamps is very large in order to obtain heating uniformity, and its control is complicated and difficult, and requires a lot of lamp supply power controllers and costs. It was also expensive. In addition, temperature calibration is required to check the power supplied to the lamp so that a uniform temperature distribution can be obtained by attaching a thermocouple to the dummy wafer before heating the wafer in actual mass production. Since the conventional high-speed lamp heat treatment apparatus heats a circular wafer with a linear lamp, precise temperature control within the wafer is difficult as described above, and temperature calibration takes time.
[0004]
[Problems to be solved by the invention]
In high-speed processing of a semiconductor IC manufacturing process, since a heat treatment is performed with a linear lamp to process a circular object to be heated (wafer), it is difficult to precisely control the temperature distribution in the wafer.
[0005]
Also, high-speed heat treatment equipment requires temperature calibration to check the power supplied to the lamp so that a uniform temperature distribution can be obtained by attaching a thermocouple to the dummy wafer before heating the wafer in actual mass production. is there. Since the conventional high-speed lamp heat treatment apparatus heats a circular wafer with a linear lamp, precise temperature control within the wafer is difficult as described above, and temperature calibration takes time.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, a high-speed lamp heat treatment apparatus in which circular lamps that are optimal for heating a circular object to be heated (wafer) and controlling the temperature distribution are arranged concentrically. Further, a linear lamp may be arranged around the circular lamp in a planar shape or a non-planar shape . Further, in the present invention, by dividing the circular lamp, it is possible to control not only the temperature distribution in the radial direction of the wafer but also the subtle temperature change in the circumferential direction or the temperature distribution when the wafer is not centrally symmetric. .
[0007]
In the present invention, it is necessary to check in advance whether a uniform temperature distribution can be obtained accurately by high-speed heat treatment, and to check the power supplied to each lamp at that time, and to apply feedback at high speed during heating. It was done automatically using a computer, making it easy and quick.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, circular lamps are arranged concentrically and each lamp has a power controller in order to individually control the power supplied to each lamp. Before repeating the high-speed heat treatment, temperature calibration is performed using a thermocouple embedded wafer. In the temperature calibration, first, the lamp supply power is calculated so that the irradiation light intensity is uniform on the wafer, and the maximum and minimum values thereof are added to the power controller for each lamp. In this case, the actual temperature distribution in the wafer becomes a convex distribution in which the wafer end temperature is lowered due to heat radiation from the wafer end. Next, the wafer inside the thermocouple is heated at 50 ° C. or 100 ° C. intervals within the maximum and minimum possible temperature range, and the difference between the wafer center temperature and the wafer edge temperature is the same as the convex temperature distribution. Each lamp power is calculated to be distributed, and the value is added to the power controller for each lamp. Each lamp power (average value of the power of each lamp that becomes the uneven temperature distribution) such that a temperature distribution intermediate between the two uneven temperature distributions is obtained is measured, and the temperature distribution in the wafer at that time is measured. The temperature distribution in the wafer (each lamp power distribution) is calculated once again to calculate the lamp power at which the intermediate temperature distribution is obtained from the uneven temperature distribution obtained previously. Measure the distribution. In the same manner, the process is repeated until the temperature distribution in the wafer approaches zero. All of these operations are performed by a computer. First, each lamp power is calculated so that the wafer has a uniform lamp irradiation light distribution, and can be automatically performed except for input to a computer.
A table showing the best temperature distribution in the wafer, power supplied to the lamp, and temperature stability control constants (P, I, D) measured at each temperature is stored in a computer. This table shows that lamp power and PID constants are functions of T for each temperature, and it is known that it is easy for a computer to match each discontinuous data to a point on a continuous function related to T. A table in which lamp power and PID constants are obtained for an arbitrary T from these continuous functions is a temperature calibration table.
[0009]
According to the present invention, when heat-treating a wafer for mass production, the wafer temperature is measured with a contact thermocouple or a non-contact thermometer, and the power distribution to each lamp for obtaining the best wafer temperature distribution from the computer according to the set temperature. Is read from the temperature calibration table and automatically heated.
[0010]
【Example】
Hereinafter, an embodiment will be described with reference to the accompanying drawings. 1 and 2, 1 is a circular lamp, 2 is an electrode for introducing current into the lamp, 3 is a water-cooled lamp light reflector, and 4 is a lamp light transmitting quartz glass. 5 is a wafer heated by lamp light, 6 and 7 are temperature detectors of a non-contact type optical fiber thermometer for measuring the center temperature of the wafer center, the edge surface and the back surface, respectively, and 8 is a temperature measurement at the center of the wafer back surface. It is a contact type thermocouple.
[0011]
Each circular lamp is connected to a power controller, and each power controller outputs power to each lamp by a signal obtained by converting the temperature measured by the wafer temperature measuring devices 6, 7, and 8 into voltage or current. . The signal to the power controller for each lamp can heat the wafer to the set temperature by comparing it with the optimum voltage or current to the power controller at each set temperature.
[0012]
Each circular lamp has a power controller, but if a temperature distribution symmetric to the wafer center is expected, the lamps are electrically parallel even if they are divided into two or more in one circle. There can be one power controller as a connection.
[0013]
The purpose of dividing one circular lamp and connecting one power controller to each lamp is to control the temperature distribution particularly when a wafer is heated to heat the wafer. Since the wafer temperature on the upstream side of the gas flow is lowered, the circular lamp is divided, and the non-contact optical fiber thermometer 6 converts the temperature of the wafer portion on the gas upstream side of the wafer into a voltage or current upstream. The temperature inside the wafer can be controlled by controlling the power supplied to the lamps 1a and 1b on the side with a power controller. In this embodiment, the two lamps on the outer periphery are divided into three parts, but the precision of the temperature control can be increased by dividing the lamps more finely.
[0014]
An embodiment of the temperature calibration method will be described with reference to FIGS. 3, 4, 6, and 7, the horizontal axis X on the wafer to be heated passes through the wafer center X, and the vertical axes in FIGS. 3 and 6 divide the power supplied to each lamp by the lamp length. The average power P of each lamp. 4, 5 and 7 indicate the temperature T on the wafer. The range of the X-axis of each plot is ± 169 mm with X0 as the center in FIGS. 3 and 6 because the lamp diameter is 338 mm (outer diameter), and ± 100 mm with X0 as the center in FIGS.
[0015]
First, the wafer is heated by supplying power so that the average power obtained by dividing the power to each lamp by the length of each lamp is the same between the lamps so that the lamp irradiation density in the wafer is constant. FIG. 3 is a graph in which the maximum (Pmax) and minimum (Pmin) of the average power of each lamp at that time are plotted in the X-axis direction.
[0016]
FIG. 3 shows the temperature distribution on the wafer (temperature distributions Tmax (X) and Tmin (X)) plotted on the wafer by measuring the temperature at each point in the wafer using a thermocouple embedded wafer with respect to Pmax and Pmin in FIG. 4. Since there is heat dissipation from the wafer edge, the temperature at the wafer edge decreases as shown in the figure. In addition, the heat radiation from the wafer edge increases as the temperature increases.
[0017]
When a φ200 wafer is heated, if the center is expressed as X0 = 10 (cm) and the wafer end is expressed as Xe = 20 (cm), the maximum temperature and the minimum in the temperature distribution of Tmax (X) and Tmin (X) in FIG. The temperature is set to T0max (= Tmax (X0)),
Temax (Tmax (Xe)), T0min (= Tmin (X0)),
Let Temin (= Tmin (Xe)). A graph as shown in FIG. 5 is obtained with the lamp average power P on the horizontal axis and the temperature T on the wafer on the vertical axis. From the graph of FIG. 5, the wafer center and the wafer edge temperature when the average power between the lamps is constant and the average power is changed can be seen. It also provides an indication of the power supplied to the individual lamps necessary for partial temperature rise of the wafer. However, if the power of the lamp that irradiates the wafer edge is increased in order to correct the wafer edge temperature according to this data, the heat at the wafer center is smaller than that at the edge. Since the electric power is increased, the temperature distribution in the wafer is not uniform only from the data of FIG.
[0018]
Next, the wafer center temperature is set to a temperature T1 having a temperature range in which the wafer is desired to be heated. From FIG. 5, it is sufficient to heat the wafer with the same average power PT1 for all the lamps with respect to the wafer center temperature T1 (= T1 (X0)), and the temperature distribution at that time is T1 (X). Since the power distribution to each lamp corresponding to T1 (X) is expressed as PT1 (X) and now PT1 is constant, PT1 (X) = PT1 as shown by the dotted line in FIG.
[0019]
Since the temperature of T1 (X) is lowered at the wafer edge, a temperature distribution in which the temperature at the wafer edge is increased is created. Therefore, PT1 (X) is multiplied by (0.001k (X−X0) ² +1) so that the lamp power increases from the wafer center toward the end. k is a positive integer.
The temperature distribution in the wafer corresponding to P′T1 (X) = (0.001k (X−X0) ² +1) PT1 (X) is defined as T1 ′ (X). The wafer is heated with a lamp power distribution of P′T1 (X), and as shown in the graph of FIG.
Heating and temperature measurement are repeated while changing k until ΔT = | T1 ′ (Xe) −T1 ′ (X0) | ≧ | T1 (Xe) −T1 (X0) |. The obtained concave wafer temperature distribution is T1 ′ (X), and the lamp power distribution is PT1 ′ (X).
[0020]
Next, a lamp power distribution is set such that the temperature distribution is intermediate between the two uneven temperature distributions T1 (X) and T1 ′ (X) in the wafer. For this purpose, the average lamp power at each X position of the lamp power distributions PT1 (X) and PT′1 (X) corresponding to each temperature distribution is calculated, and the wafer is heated. The lamp power distribution and wafer temperature distribution obtained in this way are P1T1 (X) and T11 (X) as shown in FIGS. Next, lamp power distributions (intermediate of PT1 (X) and P1T1 (X) and PT1 such that two intermediate temperature distributions of T1 (X) and T1 ′ (X) are obtained with respect to T11 (X). '(X) and P1T1 (X) may be set to an intermediate power distribution), and the temperature distribution in the wafer is measured. Similarly, the intermediate temperature distribution between the temperature distributions newly obtained for T11 (X) one after another is measured, and the temperature difference between the temperature distributions continues to 1 ° C. The temperature distribution obtained in this way, including T11 (X), is the temperature distribution having the smallest difference ΔT between the wafer center temperature and the end temperature, as described above, is Tx1 (X). Tx1 (X0) increases the peripheral lamp power with respect to the first T1 (X), and the lamp power at the center of the wafer remains unchanged, so that T1 (X0) <Tx1 (X0).
As described above, creating an uneven wafer temperature distribution is quicker to increase the precision than creating a flat wafer temperature distribution by gradually raising the peripheral temperature from the convex wafer temperature distribution. Because. In the lamp power distribution equation P′T1 (X) = (0.001k (X−X0) ² +1) PT1 (X), the lamp power change at the wafer edge is 10% when k = 1. It can be seen that, in order to approach the flat temperature distribution little by little, it is necessary to measure the temperature distribution in the wafer while changing the lamp power distribution more finely.
[0021]
A temperature distribution Tx1 (X) and a lamp power distribution PXT1 (X) having a uniform temperature inside the wafer are obtained at Tx1 different from the initial target temperature T1. In this way, the temperature distribution Tx (X) and the lamp power distribution PX (X) having a uniform temperature inside the wafer between 400 ° C. and 800 ° C. every 100 ° C. are obtained. At each temperature, the wafer center temperature by the thermocouple embedded wafer, the wafer center temperature by the non-contact type optical fiber thermometer, and the edge temperature are tabulated and stored in a computer. Since the lamp power and PID constant are functions of the wafer temperature T, if a function matching the discontinuous data is obtained, the lamp power and PID constant at an arbitrary temperature can be obtained. In this way, a temperature calibration table in which the lamp power from the set temperature 400 ° C. to 800 ° C. at intervals of 10 ° C., the PID constant, and the temperature by the contact type and non-contact type thermometer corresponding to each set temperature is completed. .
[0022]
When heat-treating a mass production wafer, the thermocouple embedded wafer is taken out and a mass production wafer is placed instead. At each set temperature, the signal corresponding to each optimum lamp supply power from the temperature calibration table is sent to the power controller of each lamp at one point on the wafer at a non-contact type optical fiber thermometer 6, 7 or contact type thermocouple. Output from the computer based on the temperature measured in step 8. When a wafer having the same emissivity as the wafer once the temperature calibration table is made is repeatedly heat-treated, only the wafer temperature measured by the non-contact type optical fiber thermometer 6 or 7 is used to transfer each lamp from the temperature calibration table to each lamp. Since the power output with the best temperature distribution in the wafer is read as the signal and each lamp power is controlled, the contact thermocouple 8 may not be used.
[0023]
When the mass production wafer is heat-treated by the high-speed lamp heat treatment apparatus of the present invention, the optimum lamp supply power is determined by measuring the front and back temperatures of the wafer 5 with the non-contact type optical fiber thermometers 6 and 7. The front and back of each are heated with different power independently with dedicated lamps. Even in the temperature calibration described above, the lamp supply power distributions on the front and back of the wafer are different, and different lamp power distributions are recorded in the temperature calibration table. Therefore, better temperature uniformity than before can be realized on the front and back of the wafer 5, and the wafer 5 with a change in the impurity distribution in the wafer 5 or in the depth direction of the wafer 5, or even on the wafer 5 with different front and back surface conditions. Warp during warmth does not occur.
[0024]
When the upstream part of the wafer is cooled by the gas flow, the temperature at the wafer surface edge (gas upstream side) is measured with a non-contact optical fiber thermometer, and the wafer surface edge at the set temperature recorded in the temperature calibration table. The lamp power of the lamps 1a and 1b in FIG. 1 is independently controlled so that the difference becomes 0, and the temperature can be made uniform.
[0025]
【The invention's effect】
As described above, according to the present invention, when a circular object to be heated (wafer) is heated, a circular lamp is used, so that the temperature distribution in the wafer is improved as compared with the conventional apparatus.
[0026]
In addition, according to the present invention, since a temperature calibration table for automatically outputting optimum lamp power from a computer during high-speed heat treatment is used, the temperature distribution in the wafer is more uniform than that of the conventional one, and In particular, a uniform temperature distribution in the wafer can be obtained.
[Brief description of the drawings]
FIG. 1 is a top view showing an embodiment of a circular lamp used in a high-speed lamp heat treatment apparatus of the present invention.
FIG. 2 is a cross-sectional view showing an embodiment of the high-speed lamp heat treatment apparatus of the present invention.
FIG. 3 is a power distribution first applied to the lamp in the temperature calibration.
FIG. 4 is a temperature distribution in a wafer in a power distribution first applied to a lamp in temperature calibration.
FIG. 5 is a graph showing the relationship between the wafer center and end temperatures and the average lamp power.
FIG. 6 is a lamp power distribution chart that gives a temperature distribution in the wafer between the concave and convex shapes at the temperature T1.
FIG. 7 is an uneven temperature distribution at temperature T1 and an intermediate temperature distribution diagram thereof.
[Explanation of symbols]
1. 1. Circular lamp Electrode 3. Water-cooled lamp light reflector 4. 4. Lamp light transmitting quartz glass Wafer 6. 6. Non-contact optical fiber thermometer temperature detector for measuring the wafer center and edge surface temperature. 7. Non-contact optical fiber thermometer temperature detector for measuring the temperature at the back of the wafer center Contact thermocouple for wafer center backside temperature measurement

Claims (6)

A heating lamp is a circular lamp, and a lamp unit including a heating lamp array arranged in a flat or non-planar shape and one or more concentric circles is arranged on one side or both sides of a sample to be heated .
Temperature calibration is performed in advance on the power distribution supplied to the heating lamp to obtain the best uniform heating temperature at each temperature of the heated object, and the temperature calibration table together with the heated object temperature distribution and the temperature stability control constant at a desired temperature. A temperature calibration table calculating means for calculating as
Storage means for storing the temperature calibration table;
When heat-treating the object to be heated, a non-contact fiber thermometer or a contact-type thermocouple that measures a point on the object to be heated to obtain a measurement temperature;
Control for obtaining an optimum supply power distribution for the heating lamp at a set temperature from the temperature calibration table based on the measured temperature and controlling the heating lamp according to the supply power distribution when the object to be heated is heated. Means,
Fast lamp heating treatment apparatus characterized by having a. The linear heating lamp is arranged on the other side of the object to be heated when the circular heating lamp is arranged on one side of the object to be heated. The high-speed lamp heat treatment apparatus described . 3. The high-speed lamp heat treatment apparatus according to claim 1, wherein one or all of the heating lamps arranged concentrically are divided into a plurality of parts within one circumference . The heating lamp is a circular lamp, and a lamp unit including one or more heating lamp arrays arranged in a flat or non-planar shape and concentrically is arranged on one or both sides of a sample to be heated, and the heating lamp is A high-speed lamp heat treatment method used when heat-treating the object to be heated,
The power distribution supplied to the heating lamp for obtaining the best uniform heating temperature at each temperature of the object to be heated is temperature calibrated in advance together with the object temperature distribution at the desired temperature and the temperature stability control constant. A first step of storing in a memory as a table;
A second step of obtaining a measurement temperature by measuring one point on the object to be heated with a non-contact type fiber thermometer or a contact type thermocouple when the object to be heated is heated;
When the object to be heated is subjected to heat treatment, an optimum supply power distribution to the heating lamp at a set temperature is obtained from the temperature calibration table based on the measured temperature, and the heating lamp is controlled according to the supply power distribution. 3 steps,
A high-speed lamp heat treatment method characterized by comprising: 5. A linear heating lamp is disposed on the other surface side of the object to be heated when the circular heating lamp is disposed on one surface side of the object to be heated. The high-speed lamp heat treatment method described. 6. The high-speed lamp heat treatment method according to claim 4, wherein one or all of the heating lamps arranged concentrically are divided into a plurality of parts within one circumference.

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