JPS60137026A - Optical irradiation heating method - Google Patents

Abstract

PURPOSE:To keep the temperature of heat treatment constnat, and to obtain a wafer having high quality by measuring the thickness of the wafer by a noncontact type sensor before the wafer is irraidiated by beams and open-controlling a pattern for the load electric power of a lamp by the measuring signal. CONSTITUTION:The thickness of a semiconductor wafer 7 is measured by a noncontact type sensor 1 before the wafer is irradiated by beams. A measuring signal from the sensor 1 is inputted to a power control section for lamps 2, and a pattern of load power for the wafer 7 thermally treated at the next cycle is determined on the basis of the measuring signal. When the wafer is thermally treated by the pattern, the heating rate and heat-treatment temperature of the wafer 7 are made constant regardless of the variability of thickness.

Description

[Detailed Description of the Invention] The present invention relates to semiconductor wafers (hereinafter simply referred to as wafers).
The present invention relates to a method of heating by light irradiation.

Among the devices generally used for heat treatment, the light irradiation furnace, which irradiates the workpiece with synchrotron radiation from an incandescent light bulb, has various special skills, so it can be used for heat treatment and drying of steel materials, plastic molding, and thermal aging tests. It is widely used in equipment, etc.

Particularly recently, processes that require heating in wafer manufacturing, such as impurity diffusion processes, chemical vapor deposition processes, crystal defect recovery processes in ion implantation layers, heat treatment processes for electrical activation, and is silicon ueno・
The use of a light irradiation furnace as a heating furnace for carrying out a heat treatment process for nitriding or oxidizing the surface layer of - in place of the conventionally used electric furnace, high frequency furnace, etc. is being investigated. In the light irradiation furnace, this may contaminate the wafer or 'r1. i: In addition to the fact that it does not give any negative atmospheric effects and has low power consumption, conventional heating furnaces cannot uniformly heat large-area wafers, and the recent increase in the size of wafers This is because it is not possible to respond to

By the way, when ion-implanted wafers are heat-treated by rapid heating in a short time using gold light irradiation, it is necessary to heat-treat the wafer in order to maintain good characteristic values such as sheet resistance and junction depth without any variation. Conditions need to be strictly controlled. , the sheet m resistance has an excellent implantation of 100 ions.
Although the junction depth does not change much if it is electrically activated, it is very important because the junction depth is greatly affected by the heat treatment temperature.

Therefore, if it were possible to directly detect the temperature of the wafer when performing rapid heating by light irradiation, and use this as feedback to control the temperature using closed control, it would be possible to
Although it becomes easier to manage heat treatment conditions, in reality, this closed control is difficult when performing high-speed heat treatment with good productivity by taking advantage of the features of light irradiation heating. Because, conventionally,
The conventional methods for measuring the temperature of a wafer have been to bring the thermocouple into direct contact with the wafer, or to expose the thermocouple to the irradiation space near the wafer. contaminated, and
This is because thermocouples and wafers are heated under different conditions by light irradiation, so there is a problem that sufficient temperature measurement accuracy, particularly quick response, and correlation between the temperatures of both cannot be obtained. Furthermore, when heating a wafer by setting it in a susceptor of an appropriate size, there is a method of embedding a thermocouple in the susceptor to measure the temperature, but this method requires sensitive temperature control because the susceptor has a large heat capacity. It is difficult to control the temperature of the wafer, does not have a fast response, and has the disadvantage that the correlation between the temperatures of the wafer and the susceptor is lost in high-speed heating.

Therefore, it is preferable to keep the heating rate constant using an oven control method based on a pre-programmed power control pattern, thereby controlling the heat treatment temperature at a constant rate.

By the way, FIG. 5 shows the temperature of the wafer and the load π1. The relationship with force is qualitatively shown, but a high load is applied for the first few seconds to rapidly raise the temperature, and when the heat treatment temperature reaches a heat treatment temperature of about 1000 to 1250℃, the load is reduced and the temperature is maintained for about 3 to 10 seconds. It is then kept and cooled down naturally. At this time, if the wafer is heat-treated with a constant load power pattern, the temperature increase rate will vary depending on the wafer, and as a result,
As shown by the dotted line in FIG. 3, the achieved temperature is different and the heat treatment temperature is constant, which affects the characteristic values of Ueno--, and the thickness of Ueno-- can be mentioned as a factor for this.

The size of Ueno-- currently used is 3 to 3 in diameter.
The diameter is about 6 inches, and the thickness at the center varies depending on the diameter, but the value is 400 to 600 μm, and there is a variation in thickness of about ±15 μm. Because of this variation, the heat capacity of the wafer differs, and if the wafer is irradiated and heated with the same load/force pattern, the heat treatment conditions (heat treatment temperature 1 hour curve) will not be constant as described above.

For example, when a wafer' with an average reflectance of 0.66 and a median thickness of 525 μm is irradiated with an intensity of 31.8 nm and heated to 1120°C for 5 seconds, the thickness It was found that when the temperature changes by 1 μm, the reached temperature changes by about 1° C., and when the temperature changes by ±15 μm, it changes by about ±15° C.

Therefore, an object of the present invention is to provide a light irradiation heating method that can keep the heat treatment conditions constant by open control when irradiating a wafer with light to rapidly raise the temperature.・The thickness of the lamp is measured with a non-contact sensor before it is irradiated with light, and the lamp's load power pattern is controlled based on this measurement signal to keep the heating rate and heat treatment temperature constant. do.

Embodiments of the present invention will be specifically described below based on the drawings.

1 and 2 show a light irradiation furnace used in an embodiment of the present invention. On the upper and lower surfaces of the furnace, 850W halogen lamps 2 are closely arranged in a planar manner, and the back A reflecting member 6 is provided so that the light emitted from the lamp 2 is directed toward the heating space 5 . A sub-reflection member 4 is also provided on the side, and a cooling channel is provided inside the reflection member 3 and the sub-reflection member 4 so that the cooling water is cooled and transmitted.

A reaction vessel 6 made of quartz glass is placed in the heating space +ijs, and a wafer 7, which is an object to be processed, is supported in the center of the interior by a support 8 made of quartz. serves also as an opening/closing door, and the support 8 is firmly attached to this opening/closing door. A carry-in conveyor 11 and a carry-out conveyor 12 for carrying 1lSi wafers 7 are arranged at the opening and closing opening of this light irradiation furnace.
The support 8 is movable between the two. A non-contact type thickness measuring sensor 1 is installed above the end of the carry-in conveyor 11, and successively measures the thickness of the wafers 7 which are being exposed to heat treatment. The sensor 1 may be of any type as long as it is a non-contact type and can therefore perform rapid measurement without contaminating the wafer 7. Then, the measurement signal from the sensor 1 is input to the power control S of the lamp 2, and based on it, the pattern of the load power for the phenol 7 to be heat-treated in the next cycle is determined. This load power pattern refers to a program of negative power values and their times as shown in Figure 6, but if the thickness of Ueno-7 is larger than the median value, the negative oil will change depending on the amount of deviation. If the force value, the time for that value, or both are increased, and the thickness is smaller than the median value, these values will be decreased, but there is a correlation between the thickness and the turn. is predetermined.Therefore, when the measurement signal from sensor 1 is input to the control unit, it corresponds to it. Ueno-7
The heating rate and heat treatment temperature are constant.

In the light irradiation furnace configured as described above, unprocessed wafers 7 are transported by the carry-in conveyor 11;
At its end, the thickness is measured by sensor 1 and transferred to support 8 outside the furnace. The wafer is then charged into the furnace and heat-treated, but as mentioned above, it is heated with a negative electric cover pattern corresponding to the thickness, so the maximum heating temperature matches the target temperature, and the 7-t resistance value of the wafer 7 and It is possible to obtain products of uniform quality without fluctuations in characteristic values such as bonding depth.

As explained above, in the present invention, the thickness of the wafer is measured with a non-contact sensor before the wafer is irradiated with light, and the pattern of the load power of the lamp is controlled in an open manner based on this 61 constant signal. , the heat treatment temperature remains constant regardless of variations in thickness, making it possible to obtain high-quality wafers. In addition, since the sensor is non-contact, it can be measured quickly within the process cycle and does not contaminate the wafer.

In this method, the heat treatment conditions are applied not only to a simple heat treatment as shown in FIG. 6, but also to a complex heat treatment curve as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of an apparatus used in an embodiment of the present invention, FIG. 2 is a plan cross-sectional view, and FIGS. 6 and 4 show one-hour heat treatment temperature fart curves. 1... Sensor 2... Lamp 6... Reflective member 6... Reaction container 7... Wafer 8... Support 11... Carrying in conveyor 12... Carrying out conveyor Applicant Ushio Inc. Company agent Patent attorney Toranosuke Tahara No. 1 Shibe 1 Figure 3 Figure 4 Be Amendment to the same procedure (spontaneous) January 30, 1985 Director of the Japan Patent Office Kami Wakasugi + 1 Husband Tono 1 Indication of the case 1988 Special Fraudulent Application No. 244321 2 Title of Invention Light Irradiation Heating Method 3 Relationship with the Amendment Case 'i! In'r appearance 1 person 4, agent name (8411) Ben + 111 person January Hara Toranosuke 5 Amendment order daily ° Spontaneous 6 Number of inventions increased by amendment / 7 Subject of amendment, Rule 1'') 'l'5' Analysis of riQ Crystal Detailed Description of the Invention Jlll 8 Contents of Amendment Attachment □JTh 1 The scope of the claims is amended as follows. In the light irradiation heating method, in which a half-fold wafer is irradiated with light to rapidly raise its temperature and then subjected to heat treatment, the thickness of the half-fold wafer is measured before it is irradiated with light, and based on this measurement result, the thickness of the half-fold wafer is measured. 1lfil 1all+ low load force pattern
- A light irradiation heating method characterized in that the degree of deformation of the hot part 3, 1, 1, and 11i is kept constant. 9 bright + f (Hμ) uniform' page 56, line 10 from line 11 1-
i K multiplied by 9th jin j1 () line 21) ji Fㅅ'
[non-consideration! Delete '6i Q resensor'. Same number a 7N 11 right eye and 1, 9th page 11fT 2nd
t・jiI square's "M11 fixed signal" to [sweat fixed button]
li i1g', do. 4. From lines 71-417 of the 1st river to J8JI 21st Street [This sensor 1 may be... "of[
This sensor 1 is limited to a non-contact type (instead, it may be a non-contact type sensor or a non-contact device such as a micrometer, but if it is a non-contact type, it will not contaminate the wafer 7. There are 41 points that can be quickly measured.
Correct to. 5. Add the following meaning to the end of the 17th line of 1if48-1. ``In addition, instead of using a non-contact inkstone or contact sensor, measure the thickness with a measuring device such as a micrometer.
As a result, a signal must be artificially input to the low-force control section. -1 6, iii O'j 49 Sada line 15, ``I made it a non-handled touch 1'' is corrected as 1-non-gray touch. that's all

Claims (1)

[Claims] In the light irradiation heating method, in which a semiconductor wafer is irradiated with light to rapidly raise its temperature and undergo heat treatment, the thickness of the semiconductor wafer is measured with a non-contact sensor before being irradiated with light, and the thickness is measured based on this measurement signal. A light irradiation heating method characterized by controlling a lamp load power pattern to maintain a constant heat treatment temperature curve per hour.