JPH07283373A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To speedily and efficiently produce devices from a semiconductor wafer by coating a resist on a wafer and photolithographically printing its surface to form an ROM code pattern on each of devices. CONSTITUTION: In step 10 a wafer to surface is, coated with a chemical resist step 20 irradiates the wafer with a light through a mask from a parallel short wavelength optical source to harden the resist on wafer regions correspond to holes of the mask, and step 30 irradiates a a part of the resist with beams at each device on the wafer, using a laser trimmer to harden the rest. The mask in step 20 is formed so as to leave unhardened resist at parts to be irradiated with other light to thereby give a slightly different pattern to each device, this identifying it with a peculiar ROM code. Thus the devices are individually produced to obtain desired devices for a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method.

[0002]

2. Description of the Related Art Semiconductor device manufacturing processes generally include
Manufacturing multiple discrete devices on a single wafer of semiconductor material. Step-and-repeat photolithographic printing with masks (step and repeat photo
Fast and efficient manufacturing processes such as lithographic printing are used to fabricate large numbers of devices on such wafers. In a lake-like iterative process, each manufacturing device is substantially identical.

However, the iterative manufacturing process as described above can produce only the same device. In some applications, individual semiconductor devices need to have unique parts. For example, a read only memory (ROM) within the device may have a small amount of unique ROM code, such as for security encryption or serial numbers.

[0004]

The problem with such applications is that semiconductor devices requiring unique parts must be manufactured individually, which makes their manufacturing extremely slow and non-comparable to the above process. It is efficient.

An object of the present invention is to provide a semiconductor device manufacturing method in which the above-mentioned drawbacks are alleviated.

[0006]

The present invention provides a method of manufacturing a semiconductor device for manufacturing a device on a semiconductor material, the method comprising applying a chemical resist to the surface of the semiconductor material; Irradiating the surface to selectively irradiate portions of the chemical resist at multiple locations to produce portions of irradiated material and portions of unirradiated material; removing either irradiated or unirradiated material from the surface The step of illuminating comprises generating a common pattern applied by the mask at each of the plurality of positions and one of a plurality of unique patterns applied to each of the plurality of positions. .

The common pattern is preferably a step
Produced by an and repeat photolithographic printing process, the unique pattern is preferably produced by a laser. Each plurality of unique patterns is preferably applied to the ROM portion of each device.

Thus, each semiconductor device can be manufactured with a different pattern and still maintain the use of a common mask. Thus, manufacturing these devices is faster and more efficient than if each device were manufactured individually.

[0009]

DETAILED DESCRIPTION Wafer form semiconductor materials are used to fabricate a large number of discrete semiconductor devices, such as microcontrollers. Processes are applied to selected areas of the wafer to modify the conductive properties of those areas. This is repeated over and over again, producing multiple layers of different regions,
The desired configuration of junctions and conductive paths is formed, resulting in a device.

Referring to the drawings, there is shown a flow chart of a semiconductor device manufacturing method for manufacturing a large number of microcontrollers on a semiconductor wafer.

The first step, represented by box 10, consists of applying a chemical resist to the top surface of the wafer. This resist typically spins the wafer at high speed,
A certain amount of chemical is applied to the center of rotation and is diffused by centrifugal force so that it is uniformly diffused on the upper surface of the wafer.

In box 20, a source of collimated short wavelength light such as ultraviolet light is emitted.
light) illuminates the wafer through the mask. The mask has a large number of holes through which light can illuminate the wafer. The areas of the wafer corresponding to the holes in the mask are illuminated by light, which changes the chemical properties of the resist in these areas. This is referred to as "curing" the resist.

The mask can be configured to manufacture one semiconductor device or many semiconductor devices at a time. In any case, the above cure is repeated at different locations on the wafer, producing a large number of semiconductor devices on the surface of the wafer. This is called step-and-repeat printing because the shape of the mask is "printed" on the surface of the resist.

In the conventional method, in box 40,
The "cured" resist is removed, exposing the above areas and leaving the rest of the wafer covered with resist. Here, the exposed regions of the wafer may be subjected to processes such as implant doping or epitaxial growth in box 50. The conductive properties of the area can be modified with respect to the remaining surface of the wafer that is not modified by this process. For example, P
The exposed areas of the mold wafer substrate can be doped such that these exposed areas are N-type, thereby forming a PN junction.

Finally, in box 60, the remaining resist is chemically removed from the surface of the wafer. Thus, the areas on the surface of the wafer have different conductive properties with respect to the remaining surface, which is the original semiconductor material.

The above conventional method produces a single layer of semiconductor material that includes regions having the characteristics of the process being applied. Each microcontroller manufactured on the wafer by the above process is substantially identical.

The microcontroller contains ROM code that is embedded in the semiconductor device. It may be desirable for each microcontroller to have a unique ROM code. The unique code can be used to identify a unique value set of each semiconductor device, and can be used for security encryption, serial number, and algorithm seed. Unfortunately, the above traditional method
Unique ROM encoding is not possible because each semiconductor device is manufactured based on the same mask pattern.

There is another way to manufacture the devices individually, which allows the coding of individual ROMs. However, such a method is slower and more expensive than the above methods.

Thus, referring again to the drawings, the step of curing the resist with masked light (Box 2
0) and the step of removing the resist (block 40), another step, box 30, is inserted. This step further applies an illuminating light source to a portion of the resist for each device on the wafer. To this end, the laser trimmer (las
er trimmer) can be used for convenience. The mask used in box 20 is configured to leave uncured resist in the areas where another irradiation light is applied. Each device is given a slightly different pattern in the above section. In this way, each device is customized for a unique ROM code.

By inserting this step, there is a slight increase in the time for the whole method, since only a small part (generally less than 0.1%) of each device has to be modified to generate the unique code. This is a significant time savings compared to the time it would take to manufacture each device individually, which would be rather time consuming.

Thus, the efficiency and speed of the step-and-repeat masking process can be combined with the individual laser printing process to enable unique ROM coding of devices such as microcontrollers.

It will be appreciated that other embodiments than the embodiments described herein are possible. For example, the curing of the resist may be configured such that the uncured portion is removed by the step indicated by box 40 rather than the cured portion as described above.

Further, instead of ROM, other elements of the device can also be modified by the steps in box 30.

[Brief description of drawings]

FIG. 1 is a flow chart of a semiconductor device manufacturing method according to the present invention.

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device for manufacturing a device on a semiconductor material, comprising: applying a chemical resist to the surface of the semiconductor material; irradiating the surface at a plurality of locations on the surface. Selectively irradiating portions of said chemical resist, thereby producing portions of irradiated material and portions of unirradiated material; removing either irradiated or unirradiated material from said surface; , The step of irradiating generates a common pattern provided by a mask at each of the plurality of positions and each one of a plurality of unique patterns provided at each of the plurality of positions. 2. The method of claim 1, wherein the common pattern is generated by a step-and-repeat photolithographic printing process. 3. The method of claim 1, wherein the unique pattern is generated by a laser. 4. The method of claim 2, wherein the unique pattern is generated by a laser. 5. The method of any of the preceding claims, wherein each one of the plurality of unique patterns is applied to a ROM portion of each device.