METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE
Provided is a method of manufacturing a semiconductor device, including: forming an active region surrounded by an element isolation region in a substrate; forming a pair of gate trenches in the active region; forming a pair of gate electrodes by embedding a conductor in the gate trenches; forming an implanted layer by implanting ions into a substrate surface between the gate electrodes; and thermally diffusing impurities of the implanted layer at least to a depth of bottom portions of the gate trenches by a transient enhanced diffusion method to form a diffusion layer region between the gate electrodes at least to a depth of bottom portions of the gate electrodes.
1 . A method of manufacturing a semiconductor device, comprising:
forming an active region surrounded by an element isolation region in a substrate;
forming a pair of gate trenches in the active region;
forming a pair of gate electrodes by embedding a conductor in the gate trenches;
forming an implanted layer by implanting ions into a substrate surface between the gate electrodes; and
thermally diffusing impurities of the implanted layer at least to a depth of bottom portions of the gate trenches by a transient enhanced diffusion method to form a diffusion layer region between the gate electrodes at least to a depth of bottom portions of the gate electrodes.
2 . A method according to claim 1 , wherein the transient enhanced diffusion method is carried out by annealing within such a temperature range that transient enhanced diffusion occurs and within such a time range that the transient enhanced diffusion is completed.
3 . A method according to claim 2 , wherein the annealing activates the impurities of the implanted layer to form an n-type impurity region.
4 . A method according to claim 2 , wherein the temperature range of the annealing falls within a range of 700 to 800° C. while the time range of the annealing falls within a range of 30 to 180 minutes.
5 . A method according to claim 2 , wherein a depth of the diffusion layer region formed by the transient enhanced diffusion method is controlled depending upon a temperature of the annealing and a dose of the ions in the implantating.
6 . A method according to claim 1 , wherein the diffusion layer region is formed only in a substrate region below a bit line contact plug.
7 . A method according to claim 1 , wherein the diffusion layer region prevents voltage change at one of the gate electrodes from affecting another of the gate electrodes between a pair of transistors adjacent to each other via the diffusion layer region.
8 . A method according to claim 1 , wherein the diffusion layer region is formed to a depth so as to cover the bottom portions of the gate trenches.
9 . A method according to claim 6 , further comprising forming a bit line on the bit line contact plug.
10 . A method according to claim 3 , wherein the n-type impurity region has a concentration of 1E18 atoms/cm 3 or more.
11 . A method according to claim 3 , wherein the n-type impurity region is formed so as to shorten a channel length of a transistor and decrease a parasitic resistance of the channel, thereby increasing an ON current of the transistor.
12 . A method according to claim 1 , wherein the implanted layer comprises the implanted impurities and crystal defects so that the diffusion layer region is formed via the crystal defects by the transient enhanced diffusion method.
13 . A method according to claim 7 , wherein the diffusion layer region serves as a drain region common to both of the transistors.